what is the value of a in the equation 3a + b = 54, when b = 9?\n15\n18\n21\n27

Answer:

A. 15

Explanation:

Step1: Substitute b value

Given the equation $3a + b=54$ and $b = 9$, we substitute $b$ into the equation: $3a+9 = 54$.

Step2: Isolate the term with a

Subtract 9 from both sides of the equation: $3a+9 - 9=54 - 9$, which simplifies to $3a=45$.

Step3: Solve for a

Divide both sides of the equation $3a = 45$ by 3: $\frac{3a}{3}=\frac{45}{3}$, so $a = 15$.