x = small popcorns
y= large popcorns
x+y=138
2.50x + 4.00y= 466.50
y = 138-x
2.50x +4.00(138-x) = 466.50
2.50x +552-4x = 466.50
2.50x-4x = 466.50 - 552
-1.5x = -85.5
-1.5x/-1.5 = -85.5/-1.5
x = 57
Since ,
x+y=138
(57)+y = 138
y = 138 - 57
y = 81
Therefore 81 large popcorns were sold!