A school has 690 Pupils and teachers altogether.

Question

A school has 690 Pupils and teachers altogether. There are 3 times as many girls as boys, there are 25 more teachers than boys. How many pupils are there? How many teachers are there?

Answer 1

G + B + T = 690

G = 3B

T = B + 25

 

 

Using the second and third equations allows replacing all variables with terms relating to boys in the first equation

 

G        +    B       +         T        = 690

 

3B       +    B       +    B + 25     = 690

 

5B + 25 = 690  

       -25    -25

 

5B    =    665       B= 665/5  =   133

 

                          T = 133+ 25 = 158

                          G = 3 * 133    = 399