The total sales this year is x (1+40/100) =1.4x, and the total expenditure is y (1+20/100) =1.2y.
x-y=20
1.4x- 1.2y=30
solve an equation
x=30 y= 10
That is, the total sales this year is1.4 * 30 = 420,000 yuan, and the total expenditure is1.2 *10 =120,000 yuan.
6.( 1) Suppose you buy X kilograms of class A fruit and Y kilograms of class B fruit.
x+y= 140
5x+9y= 1000
solve an equation
x=65 y=75
That is, 65 kilograms of fruit A and 75 kilograms of fruit B were purchased.