Question 73172
Looks like you've got the right idea but you have to be more careful with the signs (+ & -).
Solve for x:
{{{-10(8x+1)+8(10x+1) = x-9}}} Apply the distributive property.
{{{-80x-10+80x+8 = x-9}}} Combine like-terms on the left.
{{{(-80x+80x)+(-10+8) = x-9}}} Simplify.
{{{-2 = x-9}}} Add 9 to both sides.
{{{7 = x}}}
The solution is: x = 7

Check: Substitute x = 7
{{{-10(8(7)+1)+8(10(7)+1) = 7-9}}} Simplify.
{{{-10(56+1)+8(70+1) = -2}}}
{{{-10(57)+8(71) = -2}}}
{{{-570+568 = -2}}}
{{{-2 = -2}}} Check!