If the letters X and Y are used to represent two related quantities and K is used to represent their ratio (certain), the proportional relationship can be expressed by the following formula: y=k (certain) in X; If the letters X and Y are used to represent two related quantities, and K is used to represent their product (certain), the inverse ratio relationship can be expressed by the following formula: X times y=k (certain) 1, number of shares per share = total number ÷ number of shares per share = 2, 1 multiple = multiple ÷. Speed × time = distance ÷ speed = time ÷ distance ÷ time = speed 4, unit price× quantity = total price ÷ unit price = quantity ÷ total price = unit price 5, work efficiency× working time = total amount of work ÷ work efficiency = working time ÷ total amount of work ÷ working time. Minus-Minus = Difference Minus-Difference = Minus+Minus = Minus 8, Factor × Factor = Product ÷ One Factor = Another Factor 9, Divider ÷ Divider = Quotient Divider ÷ Quotient = Divider Quotient × Divider = Divider 1, Square C Perimeter S Area A Side Length Perimeter = Cube v: volume a: surface area of side length = side length× side length× 6s table =a×a×6 volume = side length× side length× side length V=a×a×a 3, circumference of rectangle c s× 2c = 2 (a+b) area = length× width S=ab 4, cuboid v: volume s:. × 2s = 2 (ab+ah+BH) triangle S area A bottom H height area = bottom X height ÷ 2s = ah 2 triangle height = area x 2 bottom triangle bottom = area x 2 height 6, parallelogram S area A bottom H height area = bottom X height s=ah 7, trapezoid S area A top bottom B bottom H height area = (upper bottom+lower bottom) Bottom area R: bottom radius C: bottom perimeter (1) lateral area = bottom perimeter × height (2) surface area = lateral area+bottom area× 2 (3) volume = bottom area× height (4) volume = lateral area ÷2× radius 10, and cone V: volume H. ÷ = decimal × multiple = large number (or decimal+difference = large number) Tree planting problem 1 Tree planting problem on the non-closed line can be mainly divided into the following three situations: (1) If trees are planted at both ends of the non-closed line, Then: number of plants = number of segments+1 = total length ÷ plant spacing-1 total length = plant spacing × (number of plants-1) plant spacing = total length ÷ (number of plants = number of nodes = total length ÷ plant spacing = Then: number of plants = number of nodes-1 = total length ÷ spacing between plants-1 total length = spacing between plants × (number of plants+1) spacing between plants = total length ÷ (number of plants +0÷ difference between two distributions = number of shares participating in distribution (. Meeting distance = speed × meeting time = meeting distance; The sum of speed and speed = meeting distance; Meeting time; Catch up with the problem; Distance = catch up with time; Distance; Speed difference = catching distance; Catch up with time; Downstream velocity = water velocity-water velocity = (downstream velocity+countercurrent velocity) ÷2 Water velocity = (downstream velocity-countercurrent velocity) ÷2 Concentration problem Solute weight+solvent weight = solution weight ÷ solution weight × 100% = concentrated solution weight × concentration = solute weight ÷. × 100% increase or decrease = principal× increase or decrease percentage discount = actual selling price ÷ original selling price× 1 00% (discount <1) interest = principal× interest rate× time after tax interest = principal× interest rate× time × (1-)