(2)2× number of girls+1= number of boys.

(3)( 1+ 1/5)× number of girls = number of boys.

(4) Q: One fifth of a number is 1, which is more than 60 than one sixth. What's this number?

Solution: let this number be X.

1/5x= 1/6x+60

x= 1800

(5) Q: Two thirds of A equals three quarters of B, and B is 80. What is a?

Solution: let a number be x.

2/3 times =80×3/4

x = 90°

(Give points)