解方程（60-2x)（40-x）=60×40÷2,(32-x)(20-x)＝540要过程

( 60 - 2x )( 40 - x ) = 60 X 40 ÷ 2
( 30 - x )( 40 - x ) = 600
( x - 30 )( x - 40 ) = 600
x" - 30x - 40x + 1200 = 600
x" - 70x + 600 = 0
x" - 10x - 60x + 600 = 0
x( x - 10 ) - 60( x - 10 ) = 0
( x - 10 )( x - 60 ) = 0
解方程得
x1 = 10
x2 = 60