b) \(\left(3x-2\right)\left(6x+1\right)+\left(2x-3\right)\left(3x+4\right)=\left(3x-5\right)\left(8x+5\right)\)
\(\Leftrightarrow18x^2+3x-12x-2+6x^2+8x-9x-12=24x^2+15x-40x-25\)
\(\Leftrightarrow24x^2-10x-14=24x^2-25x-25\)
\(\Leftrightarrow24x^2-24x^2-10x+25x=-25+14\)
\(\Leftrightarrow15x=-11\)
\(\Leftrightarrow x=\dfrac{-11}{15}\)
c) \(\left(x+3\right)\left(x-2\right)-\left(x-6\right)\left(x+7\right)=3x-17\)
\(\Leftrightarrow\left(x^2-2x+3x-6\right)-\left(x^2+7x-6x-42\right)=3x-17\)
\(\Leftrightarrow x^2+x-6-x^2-x+42=3x-17\)
\(\Leftrightarrow36=3x-17\)
\(\Leftrightarrow3x=36+17\)
\(\Leftrightarrow3x=53\)
\(\Leftrightarrow x=\dfrac{53}{3}\)
