Given that ax+3x=15

Question

1. Find the value of A when x= 3

2. Express X in terms of A

Answer 1

1)
a(3) + 3(3) = 15
3a +9=15
3a=6
a=2
2)
ax +3x=15
x(a+3)=15
x=15/(a+3)

Answer 2

both are correct

Answer 3

thanks