Question

How do you solve `A = P + Prt` for r?

Answer 1

`r = (A - P)/(Pt)`

Explanation:

Solve for r, means make r the subject of the formula, write r in terms of all the other variables.

`P + color(blue)(Prt) = A`

`" "color(blue)(Prt) = A - P " isolate the term which contains " r`

`" "Pcolor(red)(r)t = A - P`

`" "color(red)(r) = (A - P)/(Pt) " to isolate " r` divide by `P and t`