3(5-х)-х(х+2)=х(1-х)+(-2)(4-х)+7

3( 5 - x ) - x( x + 2 ) = x( 1 - x ) + ( - 2)( 4 - x ) + 7
15 - 3x - x^2 - 2x = x - x^2 - 8 + 2x + 7
15 - 5x - x^2 = - x^2 + 3x - 1
15 - 5x = 3x - 1
8x = 16
X = 2

15-3х-2х-2=х-х-8+х+7
-3х-2х-х-х+х=-8+7-15+2
-6х=-14/:(-6)
х=20