Question

Solve Q=3a+5ac for a

Answer 1

Here is how you solve... 

Q= 3a+5ac 

take out the common variable.
Q= a(3+5c)

get A by its self so divide each side by (3+5c).
Q/a(3+5c)= a(3+5c)/(3+5c)

Q/a(3+5c)=A

So your answer is A= Q/a(3+5c)

hope that helped.