SOLUTION
Consider the diagram below
Applying the rule in the diagram above, we have
[tex]|QR|=\frac{1}{2}(|ON|+|PM|)[/tex]Recall from the questions
[tex]\begin{gathered} |QR|=33 \\ |ON|=3x-8 \\ |PM|=7x+4 \end{gathered}[/tex]Then we substitute the parameters above into the expression above
[tex]\begin{gathered} 33=\frac{1}{2}(3x-8+7x+4) \\ \text{ Multiply both sides by 2} \\ 66=3x-8+7x+4 \\ \text{rerrange the terms and simplify } \\ 66=10x-4 \\ \text{collect like terms } \\ 66+4=10x \end{gathered}[/tex]simplify further
[tex]\begin{gathered} 70=10x \\ \text{divide both sides by 10} \\ x=\frac{70}{10} \\ \text{then} \\ x=7 \end{gathered}[/tex]Therefore the value of x is 7
Therefore the right option is E
