Solve $5x + 3y = 29$ and $2x - 3y = -1$. What is the value of $y$?

Explanation

1. 01

   Add the two equations: the $y$ terms cancel and $7x = 28$, so $x = 4$.

2. 02

   Put $x = 4$ in the first equation: $20 + 3y = 29$, so $3y = 9$.

3. 03

   Hence $y = 3$.