Question

what is the value of a in the equation 3a + b = 54, when b = 9?
○ 15
○ 18
○ 21
○ 27

Explanation:

Step1: Substitute \( b = 9 \) into the equation

We have the equation \( 3a + b = 54 \). Substitute \( b = 9 \) into it, so we get \( 3a + 9 = 54 \).

Step2: Solve for \( 3a \)

Subtract 9 from both sides of the equation: \( 3a = 54 - 9 \). Calculate the right side: \( 54 - 9 = 45 \), so \( 3a = 45 \).

Step3: Solve for \( a \)

Divide both sides of the equation \( 3a = 45 \) by 3: \( a=\frac{45}{3}=15 \).

Answer:

15