Question 191854
Let  A  =  adult  price
let  C = Child  price

1)   2A+3C=40,5

2)  3A+1C=38.00

mult  (2)  by  3

9A+3C=114.00

subtract  (1)

7A +0C=  73.50
divide  by  7,  both  sides  of  eqn

A=10.50

subst  in  (1)

2(10.5)  +  3C = 40,50
21.00  +3C= 40.50

subtract     21.00  both  sides

3C=  19.50
divide  both  sides  by  3

C=6.50

check

2(10,50) + 3(6.50)=  21 + 19.50 = 40.50    ok

3(10.50) + 6.50 = 31.50 + 6.50 = 38.00    ok