The denominator (the part under the "/") need to be the same to add fractions. You need to transform them into the smallest common denominator. In this case it will be 56 (no other smaller number can be found that can be divided by both 8 and 7. Note that it would also work if the denominator is larger than this as long as it can be divided without remain by both 8 and 7.

Doing that change the value of each number. To equilibrate it back, we need to multiply the number on top (the numerator) also by the amount we multiplied under it. this give:

((7x5)/56) + ((8x1)/56) = (35/56) + (8/56) = 43/56 or 0.76785714285714... in decimal form (it give a periodic decimal part).

Edited by Martin on 1/28/2010 at 1:03 AM EST

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