Rewrite the equation as .

Divide each term in by .

Cancel the common factor of .

Cancel the common factor.

Divide by .

Subtract from both sides of the equation.

Divide each term in by .

Cancel the common factor of .

Cancel the common factor.

Divide by .

Simplify each term.

Multiply and .

Move the negative in front of the fraction.

Solve for r a=p(1+nr)