The combined capacity of a bottle and a glass is equal to the capacity of a pitcher. The capacity of a bottle is equal to the combined capacity of a glass and a mug. The combined capacity of three mugs is equal to the combined capacity of two pitchers. How many glasses altogether have the capacity of one mug?

A) 3
B) 4
C) 5
D) 6
E) 7

1 answer

bottle -- b
glass --- g
pitcher --- p
mug -----m

p = b+g
b = g+m
3m = 2p

all up all 3 equations:
p+b+3m = b+2g+m+2p
2m=p+2g
2m = b+g + 2g = b+3g
2m = g+m + 3g
m = 4g

4 glasses make up a mug.