Start with
[tex] -4 = \dfrac{3}{4}(x+8) [/tex]
Multiply both sides by 4:
[tex] -16 = 3(x+8) [/tex]
Divide both sides by 3:
[tex] -\dfrac{16}{3} = x+8 [/tex]
Subtract 8 from both sides:
[tex] x = -\dfrac{16}{3}-8 = -\dfrac{16}{3}-\dfrac{24}{3} = -\dfrac{40}{3} [/tex]
