first class tickets = 3
coach tickets = 2
Explanation:
let number of coach tickets = x
and
number of first class tickets = y
coach tickets + first class tickets = total tickets
x + y = 5 -----> equation A
now
total cost of coach tickets = cost per coach tickets * number of coach tickets
= 120 * x
and
total cost of first class tickets = cost per first class ticket * number of first class tickets
= 990 * y
cost of coach tickets + cost of first class tickets = total cost of tickets
120x + 990y = 3210 -----> equation B
equation B - 120 times equation A gives
120x + 990y - 120 (x + y) = 3210 - 120 * 5
120x + 990y - 120x - 120y = 3210 - 600
870y = 2610
y = 3
thus x + 3 = 5
or x = 2