3a + 4b = 4.85....multiply by 4
4a + 10b = 8.75...multiply by -3
-------------------
12a + 16b = 19.40...result of multiplying by 4
-12a - 30b = - 26.25...result of multiplying by -3
------------------add
-14b = - 6.85
b = -6.85 / -14
b = 0.489 rounds to 0.49 <== price per banana
3a + 4b = 4.85
3a + 4(0.49) = 4.85
3a + 1.96 = 4.85
3a = 4.85 - 1.96
3a = 2.89
a = 2.89/3
a = 0.963 rounds to 0.96 <== price per apple
