number me integers between then is =51
no divisible by 3:
no divisible by 5:
now strike out 105 120 135 150,as it is present in both.
EDIT: I guess I should make up for it now; you could do 1 dollar/4. You could also, do 5/2, than move the decimal over two spaces.
As you can see, there are many problem solving applications which can be applied in these type of problems, most of which involve reducing the total sum in order to make the problem less complicated and than adding it on after you recieve your answer.