Question

Given the equation 4x + 7 = 3(2x − 5), solve for the variable. Explain each step and justify your process.
B.Sam solved a similar equation below. Is Sam's solution correct? Explain why or why not.
5x − 1 = 2(x + 4)
5x − 1 = 2x + 8
7x − 1 = 8
7x = 7
x = 1

Answer 1

Part 1: $4x + 7 = 3(2x - 5)$ 

$4x+7=6x-15$ 

$7=6x-15-4x$ 

$7=2x-15$ 

$7+15=2x$ 

$22=2x$ 

$22=2x / 2$ 

$x=11$ 

Part 2: Sam is not correct because he messed up the second step. He added 2x on both sides to get 7x, instead he should have subtracted.