Question

已知x+2y=5,求代数式3x+6y的值,那么代数式5x+10y-10的值

Answer 1

x+2y=5,

∴3x+6y

=3(x+2y)

=3×5

=15

5x+10y-10

=5(x+2y)-10

=5×5-10

=15