Perimeter = length of all sides added together
\(102=(3x+5)+(3x+5)+(7x-4)+(7x-4)\)
\(102=2(3x+5)+2(7x-4)\)
\(102=6x+10+14x-8\)
\(102=20x+2\)
\(102-2=20x\)
\(100=20x\)
\(x= \frac{100}{20}\)
\(\left[\begin{array}{ccc}x=5\end{array}\right]\)
Hope this helped
