Question

There are 75 students in classes A and B altogether. There are 61 students in classes A and C altogether. The ratio of the number of students in Class B to Class C is 5:3. How many students are there in Class A?

Answer 1

40

Explanation:

A + B=75

A + C = 61

B = 5/3 *C

A+C * 5/3 = 75 then we got the answer

Answer 2

A = 40

Explanation:

A+B = 75

A+C = 61

Subtract

A+B = 75

-A-C = -61

----------------------

B-C = 14

B:C

5:3

for every 5B there are 3C

Replace B with 5/3 C

5/3C-C = 14

2/3C = 14

C = 21

A+C = 61

A +21 = 61

A = 40