1, number of copies × number of copies = total number of copies-number of copies = total number of copies-number of copies = number of copies = number of copies.

2, 1 multiple × multiple = multiple-1 multiple = multiple-multiple = 1 multiple

3. Speed × time = distance-speed = time-time = speed.

encounter a problem

Meet distance = speed and x meet time = meet distance-sum of speed and speed = meet distance-meet time and problem catching distance = speed difference × catching time = catching distance-speed difference speed difference = catching distance-catching time.

Tap water problem

Downstream speed-still water speed+countercurrent speed-still water speed-water flow speed-still water speed = (downstream speed+countercurrent speed) ÷2 Water flow speed = (downstream speed-countercurrent speed) ÷2

Concentration problem: solute weight+solvent weight = solution weight × 100%= concentration solution weight× concentration = solute weight-concentration = solution weight.

Profit and discount: profit = selling price-cost profit rate = profit-cost × 100%= (selling price ÷ cost-1)× 100% fluctuation amount = principal x fluctuation percentage discount = actual selling price ÷ original selling price ×/kloc-0. 1) interest = principal × interest rate× after-tax time interest = principal × interest rate× time x( 1-20%)

Area and volume conversion

(1) 1 km = 1 km = 1 000m/m = 10 decimeter 1 cm = 1 cm =/kloc.