Question

M-2M-6M=90+3M
10X=9+4+51

Answer 1

$m-2m-6m=90+3m\to \\\\m-2m-6m-3m=90\to\\\\ -10m=90\to \\\\m= \frac{90}{-10} \to\\\\ m=-9 \\\\\\\\\\\\\\10x=9+4+51\to\\\\ 10x=64\to\\\\ x= \frac{64}{10} \to\\\\x=6,4$