First, find a common denominator (preferably the LCD): 8 and 6 both factors of 24, which is also the LCM, so we'll use that.
Second, manipulate the numerators so that the fractions are equivalent to the ones you started-out with: In order to make 7/8 equal to a fraction that has a denominator of 24, we have to multiply the numerator by 3, since we multiplied the denominator by 3 to make it 24. We will do the same process for the fraction 4/6.
Thus far, we should have 21/24 plus 16/24.
Next, all we have to do is add the numerators together, and keep the denominator. You should end-up with 37/24. If your teacher doesn't want an improper fraction, we can simplify this by dividing 37 by 24, which gives us 1, and then subtracting 24 from 37 in order to find-out how many twenty-fourths we have left over. Since this is equal to 13, the mixed-number form of the answer would be 1 13/24 ("one and thirteen twenty-fourths").
