Answer - ? = 43
Explanation -
Let the pair of shoes be, S
Let the boy be, B
& The popcorn be, P
Converting the above equations in the form of the above terms.
Equation (1); S + S + S = 30
Equation (2); B + B + S = 20
Equation (3); 2P + 2P + B = 13
Equation (4); (0.5)S + (B + 2P + S) * P = ?
Now, solve equation(1);
S + S + S = 30
3S = 30
S = 10
Substitute the value of S, in equation(2)
B + B + S = 20
2B + 10 = 20
2B = 10
B = 5
Similarly, substitute B in equation(3);
2P + 2P + B = 13
4P + 5 = 13
4P = 8
P = 2
Now, substitute all the values for final equation(4);
(0.5)S + (B + 2P + S) * P = ?
= (0.5)10 + (5 + 2*2 + 10) * 2
= 5 + (5 + 4 + 10) * 2
(0.5)S + (B + 2P + S) * P = 5 + 38
(0.5)S + (B + 2P + S) * P = 43