Question

4×(2х-3у)-7×(4х-5у)
Если: х= -0,2
у= 0,6

Answer 1

$4*(2x-3y)-7*(4x-5y)=4*2x-4*3y-7*4x-7*(-5y)=$
$=8x-12y-28x+35y=8x-28x-12y+35y=-20x+23y$
$=-20*(-0.2)+23*(0.6)=20* frac{1}{5}+23* frac{3}{5}= frac{20*1+23*3}{5} = frac{89}{5} =17.8$