To rearrange the formula \( A = P + Prt \) and solve for \( r \), we want to isolate \( r \) as the quantity of interest.
The formula can be rewritten as:
\[
A = P(1 + rt)
\]
Here’s a breakdown of how we can isolate \( r \):
- First, we need to get rid of \( P \) from the right side of the equation.
Looking at the choices:
a. Subtract \( P \) from both sides of the equation.
- This would give us \( A - P = Prt \), which is correct to isolate the \( Prt \) term but still leaves \( r \) multiplied by \( t \).
b. Divide both sides by \( t \).
- This would not be applicable in the first step because we haven’t isolated anything involving \( t \) yet.
c. Subtract \( Pr \) from both sides.
- This does not make sense as we would not isolate \( r \) by doing this.
d. Divide both sides by \( P \).
- This is a good step, but we would first want to get rid of the \( P(1 + rt) \) term entirely before we can isolate \( r \).
Therefore, the Correct First Step:
The best choice for the first step would be a. Subtract \( P \) from both sides of the equation.
Work:
-
Starting from \( A = P + Prt \):
\[
A - P = Prt
\]
-
The next steps would then involve dividing by \( Pt \) to isolate \( r \).
So, in summary, the first step is: a. Subtract \( P \) from both sides of the equation.