Answer
The system has infinitely many solutions.
Work Step by Step
So, from equation (I) put the value of y in equation (II) and solve for x,
$\begin{align}
& 21x-35=7\left( 3x-5 \right) \\
& 21x-35=21x-35
\end{align}$
$35=35$ (III)
And according to equation (III), $35=35$ indicates that the system has infinitely many solutions.
