Question

What value of x makes the equation 15 - 7x = 5x - 21 true?

A) x = -3
B) x = -12
C) x = 3
D) x = 12

Answer 1

To solve the equation 15 - 7x = 5x - 21, we first move all x terms to one side and constants to the opposite side by performing addition or subtraction. Then we divide both sides of the equation by the coefficient of x to find x = 3, which is answer choice C.

Step-by-step explanation:

To find the value of x that makes the equation 15 - 7x = 5x - 21 true, we must perform a series of algebraic steps to isolate x. We start by adding 7x to both sides of the equation to move all the x terms to one side. This gives us:

15 = 12x - 21

Next, add 21 to both sides of the equation to get all constant terms on the opposite side:

15 + 21 = 12x

Then we simplify the left side:

36 = 12x

Finally, to solve for x, divide both sides of the equation by 12:

x = 36 / 12

x = 3

Therefore, the correct answer is C) x = 3.