Question

Сос
(8х+3)-(10х+6)=9

Answer 1

(8x+3)-(10x+6)=9
8x+3-10x-6=9
-2x=12
x=-6                    

Answer 2

$8x + 3 - 10x - 6 = 9 \\ - 2x - 3 = 9 \\ - 2x = 9 + 3$
$- 2x = 12 \\ x = 12 \div ( - 2) \\ x = - 6$