Let's make a system of equations.
1 large bottle = l
1 regular bottle = r
l + r = 113
221 = 2.5l + r
Isolate r in the first equation and substitute it into the second equation:
l + r = 113
r = 113 - l
---
221 = 2.5l + 113 - l
221 = 1.5l + 113
108 = 1.5l
72 = l
Now, substitute that back into the first equation:
l + r = 113
72 + r = 113
r = 41
Finally, check your work by substituting back into both equations:
72 + 41 = 113 --> 113 = 113 <-- True
221 = 2.5(72) + 41 --> 221 = 180 + 41 <--True
Answer:
Franklin sold 72 large bottle of water and 41 regular-sized bottles of water.
