Liam thinks of a number . He multiplies the number by 5 and then subtracts 60 form the result .his answer equals the number he started with : what was the number Liam started with ?

To find this answer you can use a guess and check method.

 Start with 1.

1 x 5 = 5
5 - 60 will not work

Try 10

10 x 5 = 50
50 - 60 will not work

Try 20 
20 x 5 = 100
100 - 60 will not work

Try 15

15 x 5 = 75
75 - 60 = 15

The answer is 15.