well, to add and subtract unlike fractions, you need to look at both fractions and look at their denominators. next, you need to find the LCD, or the least common denominator. for example : 1/3 + 3/5. what is the least common multiple of 3 and 5? its 15 . and after that , you multiply the top the same amount you multiplied the bottom by, example con. : 1/3 x 5/5= 5/15 and 3/5 x 3/3 = 9/15. then you add the products , 5/15 + 9/15 and you get 14/15.
