For what ordered pair $(a,b)$ are there infinite solutions $(x,y)$ to the system \begin{align*} 2ax+2y&=b,\\ 5x+y&=-3. \end{align*}
2ax+2y=b
5x+ y= -3 ⇒ 10x + 2y = -6
So.....we will have infinite solutions when
2a = 10 ⇒ a = 5
And
b = -6
So { a, b} = { 5, -6 }
