find a common denominator. for example the third question is 2/3-2/5. the common denominator would be 15 because both are divisible by 15. since you multiply three, 5 times to get 15 you multiply 2 by 5 which is ten (new fraction is 10/15). then the other is 2/5 so same thing with the other one it takes three fives to get to 15 so its 2 times 3 which is six (new fraction is 6/15) you have to qual out each side. 10/15-6/15 is 4/15
