\(\left(y+1\right)+\left(y+2\right)+\left(y+3\right)+\left(y+4\right)+...+\left(y+37\right)=999\)
\(y+y+y+y+...+y+1+2+3+4+...+37=999\) ( 37 số y )
Phần 1 + 2 + 3 + 4 + ... + 37 có : ( 37 - 1 ) / 1 + 1 = 37 ( số hạng )
\(\Rightarrow37y+\frac{\left(37+1\right)37}{2}=999\)
\(37y+703=999\)
\(37y=999-703\)
\(37y=296\)
\(y=\frac{296}{37}=8\)