Answer:
b. [tex]\frac{52}{3}[/tex]
Step-by-step explanation:
From the diagram shown,
There are 3 parallel lines cut by 2 non-parallel transversals.
According to the triangular proportionality theorem extension to parallel lines cut by transversals,
The ratio of lengths of transversals are proportional to each other.
Therefore,
[tex]\frac{3x}{4x}=\frac{3x+7}{5x-8}\\\frac{3}{4}=\frac{3x+7}{5x-8}\\3(5x-8)=4(3x+7)\\15x-24=12x+28\\15x-12x=28+24\\3x=52\\x=\frac{52}{3}[/tex]
Hence, the correct option is b.