Question

Change the subject of the formula S=P(1+rt) to t

Answer 1

$S=P(1+rt) \\S\div P=1+rt \\(S\div P)-1=rt \\t= \frac{(S\div P)-1}{r}$

Answer 2

So you basically want t=something

so s=p(1+rt)
divide both sdies by p
s/p=1+rt
subtract 1
(s/p)-1=rt
divide by r
[(s/p)-1]/r=t