Answer:
The cost of student ticket is $4
Step-by-step explanation:
let
price for an adult = a
price for a student = b
7a + 16b = 120...........(i)
13a + 9b = 140............(ii)
make a subject of the formula in equation(i)
7a = 120 - 16b
divide through by 7
a = 120/7 - 16/7b
insert a in equation(ii)
13(120/7 - 16b/7) + 9b = 140
1560
/7 - 208b/7 + 9b = 140
collect like terms
(-208b + 63b)/7 = 140 - 1560/7
-145b/7 =(980 - 1560) /7
-145b/7 = -580/7
multiply both sides by 7
-145b = -580
divide both sides by -145
b = -580/-145
b = 4
Insert the value of b in equation(ii)
13a + 9b = 140............(ii)
13a + 9(4) = 140
13a + 36 = 140
13a = 140 - 36
13a = 104
divide both sides by 13
a = 104/13
a = 8
The cost of student ticket is $4
