The possibility of your next question being noob is approximately 29 over 16.
(4/9) x = That's not an equation. If there were a number after the 'equals' sign, then we could calculate the value of 'x'. But as it is, there's no question there, so there's nothing to solve.
Your question is not very clear. Are you asking: solve for x where negative 4 over x equals negative 20. x equals 1/5 (one fifth)
To solve for x, we'd have to know what this expression equals.
d = -196
x=12
c equals b over 8
It equals 2 over 8.
Is it 15 over 40?
x is 9.
X = 32
x equals 4 over 35