first you want to turn both fractions into improper fractions. So 1 4/7 would now be 11/7 because 1 x 7 + 4 is 11. And -1 4/8 will now be -12/8 because 1 x 8 + 4 is 12. Now you must find the common denominator. 8 x 7 is equal to 56 so the common denominator is 56. So now we are adding 11/56 + (-12/56). 11 plus 12 is 23. So we have 23/56. 23 can go into 56 two times because 23 x 2 = 46. There is 10 left over so our final answer is -2 10/56. In simplest form our answer would be -2 5/28
