Question

Maths question: 30 POINTS

Four boys Alex, Bryan, Calvin and Derrick, each have some stamps. The number of stamps Alex has is 1/2 of the total number of stamps Alex, Calvin and Derrick have. The number of of stamps Calvin has 1/4 of the total stamps Alex, Bryan and Derrick have. If Derrick has 78 stamps, find the total number of stamps Alex and Bryan have altogether.

Answer 1

A = (1/2)(B + C + D) ⇒ 2A = B + C + D

B = (1/3)(A + C + D) ⇒ 3B = A + C + D

C = (1/4)(A + B + D) ⇒ 4C = A + B + D

D = 78

Substitute 78 for D. Solve the three equations in three variables