9514 1404 393
Answer:
Explanation:
If we let a, b, c represent tickets booked on airlines A, B, C, respectively, then we have ...
a + b + c = 55
a - b = 6
-2b + c = 5
Using the last two equations to write expressions for a and c, we have ...
a = b +6
c = 5 +2b
These can be substituted into the first equation to give ...
(b +6) +b +(5 +2b) = 55
4b +11 = 55
4b = 44
b = 11
a = b+6 = 17
c = 5 +2b = 27
He booked 17 tickets on Airline A, 11 tickets on Airline B, and 27 tickets on Airline C.