a.\(\Leftrightarrow\left(x-2\right)\left(x-5\right)=\left(x-2\right)\left(x+2\right)\)
\(\Leftrightarrow\left(x-2\right)\left(x-5\right)-\left(x-2\right)\left(x+2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x-5-x-2\right)=0\)
\(\Leftrightarrow-7\left(x-2\right)=0\)
\(\Leftrightarrow x=2\)
b.\(\Leftrightarrow\dfrac{5\left(7x-1\right)+60x}{30}=\dfrac{6\left(16-x\right)}{30}\)
\(\Leftrightarrow5\left(7x-1\right)+60x=6\left(16-x\right)\)
\(\Leftrightarrow35x-5+60x=96-6x\)
\(\Leftrightarrow101x=101\)
\(\Leftrightarrow x=1\)