How many students in Mrs. Moore's class are taking Chinese?

Three foreign languages are offered in Lincoln Elementary School: Spanish, French and Chinese. In Mrs. Moore's class every student takes one and only one foreign language class. There are 14 students taking either Spanish or French. There are 18 students taking either Spanish or Chinese and there are 16 students taking either French or Chinese. How many students in Mrs. Moore's class are taking Chinese?

MetroEye: Every student takes one and only one foreign language class.

Let number of Spanish students be S, number of Chinese students be C and number of French students be F.

As per Metro Key,
S+F=14 .....(1)
S+C=18 .....(2)
F+C=16 .....(3)

Solving above equations (1) and (2)
(2)-(1) gives C-F=4 ....(4)

Adding equations (3) and (4)
2C=20 => C=10

10 Students in Mrs.Moore's class takes Chinese.