LAST ATTEMPT IM MARKING AS BRAINLIEST!! (Finding missing sides- similar triangles Algebraic practice )

Answer:
x=3
Step-by-step explanation:
What u should always do is look at the letters of the triangles given:
It will tell u that:
[tex] \frac{tu}{dc} = \frac{uv}{cb} [/tex]
Now we once again just sub in the values:
[tex] \frac{12}{9} = \frac{20}{4x + 3} [/tex]
we can simplify the fraction on the right
[tex] \frac{4}{3} = \frac{20}{4x + 3} [/tex]
And now we cross multiply
3×20=4(4x+3)
60=16x+12
60-12=16x
48=16x
Therefore :
x=3