Answer:
Adult ticket= 7£
Child ticket= 2£
Step-by-step explanation:
Let the cost of an adult ticket be £A and the cost of a child ticket be £C.
2A +3C= 20 -----(1)
A +4C= 15 -----(2)
From (2):
A= 15 -4C -----(3)
Susbt. (3) into (1):
2(15 -4C) +3C= 20
30 -8C +3C= 20 (expand)
30 -5C= 20 (simplify)
5C= 30 -20
5C= 10
C= 10 ÷5
C= 2
Subst. C=2 into (3):
A= 15 -4(2)
A= 15 -8
A= 7
Thus, the cost of an adult ticket and a child ticket is 7£ and 2£ respectively.
