A tutoring program serves a total of 22 students who are either 15 or 16 years old. The sum of the students' ages is 343. How many 15-year-old students does the tutoring program serve?

Answer: 9

Step-by-step explanation:

If you let x be the amount of 15 year olds and y to be the amount of 16 year olds.

x+y=22 15x + 16y = 343

So

y = 22-x

15x + 16 (22 - x) = 343

15x + 352 - 16x = 343

-x = - 9

So x = 9

Therefore 9 15 year olds are on the program