I really suck at math, but I think I can get this one. Find a common denominator, like you have 2/5 the next number they both go into is 10. So 2 fives make ten. Then you have to multiply the 2 by the same 2 like you did with the 5. This will give you 4/10, the four is four of ten, so the percent is 40%, if you add a zero to both numbers 40/100, we know that is 40%. Percents are easier for me, because I worked as a waitress, and we know how much our tip should be according to the service we gave, and the percents.