a)Ta có:
\(-12\left(x-5\right)+7\left(3-x\right)=5\)
\(\Rightarrow-12x+60+21-7x=5\)
\(\Rightarrow60+21-5=12x+7x\)
\(\Rightarrow76=19x\Rightarrow x=4\)
b)Ta có:
\(30\left(x+2\right)-6\left(x-5\right)-24x=100\)
\(\Rightarrow30x+60-6x+30-24x=100\)
\(\Rightarrow30x-6x-24x=100-60-30\)
\(\Rightarrow0x=10\), vô lí
Vậy không có x thỏa mãn