Question

$\frac{x}{10} - 10 = \frac{x-61}{20}$

Answer 1

$\displaystyle\frac{x}{10} -10=\frac{x-61}{20} \\2x-200=x-61\\2x-x=-61+200\\x=139$

Answer 2

$\frac{x}{10}-10=\frac{x-61}{20}\\\\\frac{x}{10}*20-10*20=\frac{x-61}{20}*20\\\\2x-200=x-61\\\\2x-x=200-61\\\\x=139\\\\Otvet:\boxed{139}$