For this case, we must clear variable "x" from the given equation, expressed in terms of "a".
We have:
[tex]\frac {3} {a} x-4 = 20[/tex]
By clearing "x" we have:
Adding 4 to both sides of the equation:
[tex]\frac {3} {a} x = 20 + 4[/tex]
Multiplying by[tex]\frac {a} {3}[/tex] on both sides of the equation:
[tex]x = \frac {24a} {3}\\x = 8a[/tex]
So,[tex]x = 8a[/tex]
Answer:
[tex]x = 8a[/tex]