Solve Each System by Using Either the Substitution or the Elimination-By-Addition

Multiple Choice

Solve each system by using either the substitution or the elimination-by-addition method, whichever seems more appropriate. $$\left( \begin{array} { c } 3 x - y = 7 \\5 x + 10 y = 1\end{array} \right)$$

A) $\left( \frac { 71 } { 35 } , \frac { 32 } { 35 } \right)$
B) $\left( - \frac { 71 } { 35 } , \frac { 32 } { 35 } \right)$
C) $\left( \frac { 71 } { 35 } , - \frac { 32 } { 35 } \right)$
D) no solutions
E) infinitely many solutions