8x = 7x + 3
would i combine the 8x and the 7x at all in this equation?

Yes...thats what u want to do. you want to get the x terms on one side and everything else on the other side.

8x = 7x + 3so we will subtract 7x from both sides
8x - 7x = 7x - 7x + 3simplify
1x, or just x = 3 (because ur 7x's cancelled each other out)

so ur answer is : x = 3

and u can check ur answer by subbing it back into the original equation.
8x = 7x + 3
8(3) = 7(3) + 3
24 = 21 + 3
24 = 24 (correct)

3cm and 6 and 9 cm that a possibility of that question

128/3reason being 5 and 1/3 = 16/316/3 • 2/3 = 32/31 and 1/3 = 4/3 32/3 • 4/3 this will equal 128/3