If the system {ax+2y=53x+4y=10\begin{cases} ax + 2y = 5 \\ 3x + 4y = 10 \end{cases}{ax+2y=53x+4y=10 has infinitely many solutions, what is aaa?
a=32a = \frac{3}{2}a=23
a=2a = 2a=2
a=1a = 1a=1
a=12a = \frac{1}{2}a=21