Hey there!
4 + 5x + 66 = x + 10
70 + 5x = x + 10
5x + 70 = x + 10
SUBTRACT x to BOTH SIDES
5x + 70 - x = x + 10 - x
5x + 70 - 1x = 1x + 10 - 1x
SIMPLIFY IT!
4x + 70 = 10
SUBTRACT 70 to BOTH SIDES
4x + 70 - 70 = 10 - 70
SIMPLIFY IT!
4x = -60
DIVIDE 4 to BOTH SIDES
4x/4 = -60/4
SIMPLIFY IT!
x = -60/4
x = -15
Therefore, your answer is: x = -15
Good luck on your assignment & enjoy your day!
~Amphitrite1040:)