d=David's bowling score
a=Aaron's bowling score
-----------------------------------
d=3a-5
-----------------------------------
a+d=215
---------------------------
If:
a+d=215
d=215-a
---------------------------
If d=215-a
215-a=3a-5
215+5=3a+a
220=4a
a=220/4
a=55
--------------------------
If a=55,
d=215-55
d=160
---------------------------
David's bowling score was 160.
Aaron's bowling score was 55.
