Question

Make t the subject of the formula: S = at + bt

Answer 1

To make t the subject is basically isolating t

S = at + bt
We see on the right side that t is common, so we factor it out.

S = t(a + b)
Divide by (a+b) to isolate t

$\frac{S}{a + b} = \frac{t(a+b)}{(a+b)}$
a + b and a + b cancels out
We are left with the answer:
t = $\frac{S}{a+b}$

Answer 2

$S = at + bt \\ t(a+b)=S\\ t=\dfrac{S}{a+b}$