We have this system
2a + 3c = 61
3a + 5c = 96
Multiply the first equation through by 3 and the second through by -2 and we have
6a + 9c = 183
-6a -10c = - 192 add these
-c = - 9
c = 9
And to find a
2a + 3(9) = 61
2a + 27 = 61 subtract 27 from both sides
2a = 34 divide both sides by 2
a = 17
So (a, c) = (17, 9)