Please post your test problems this way:

• Problem:(answer,level of difficulty(easy, medium, hard))
• Example

　${\displaystyle x+11=36}$:

(${\displaystyle x=36-11=25}$,  easy)

${\displaystyle {\begin{cases}x+11=y+111\\y=-3x\end{cases}}}$

${\displaystyle x+11=-3x+111}$

${\displaystyle x=25}$ ,(${\displaystyle 25+11=36}$)

(${\displaystyle y=36-111=-75}$, medium)