Question

1. which of the following equations is equivalent to ( x - 3y = 21 )?

a. ( y = -\frac{1}{3}x + 7 )
b. ( y = \frac{1}{3}x - 7 )
c. ( y = -3x - 7 )
d. ( y = 3x + 7 )

Explanation:

Step1: Isolate -3y

Start with the equation \( x - 3y = 21 \). Subtract \( x \) from both sides to get \( -3y = -x + 21 \).

Step2: Solve for y

Divide every term by -3. So, \( y=\frac{-x + 21}{-3}=\frac{1}{3}x - 7 \).

Answer:

B. \( y=\frac{1}{3}x - 7 \)