Answer:
C. 7
Step-by-step explanation:
[tex] In\: \triangle ABC\\
\overline{PQ} \parallel \overline {BC}.. (given) \\[/tex]
Therefore, by Basic Proportionality theorem:
[tex] \frac{AP}{PB} = \frac{AQ}{QC} \\\\
\therefore \frac{x}{x+7} = \frac{x-3}{x+1} \\\\
\therefore \: \frac{x - x - 7}{x + 7} = \frac{x - 3 - x - 1}{x + 1} \\ (by \: dividendo) \\ \\ \frac{ - 7}{x + 7} = \frac{ - 4}{x + 1} \\ \\ \frac{7}{x + 7} = \frac{4}{x + 1} \\ \\ 7x + 7 = 4x + 28 \\ \\ 7x - 4x = 28 - 7 \\ \\ 3x = 21 \\ \\ x = \frac{21}{3} \\ \\ \huge \red{ \boxed{ x = 7}}[/tex]
