When you're adding fractions with two different denominators, the best thing to do is to find a common denominator; In this case, 4 and 8 are both multiples of 8, and therefore, you've got to double the first fraction. Doubling the first fraction gives you 2/8 and 3/8. You've then got to add these together, and this gives you 5/8 (as you only add the numerators) As you're looking for what is left, you have to do 8/8- 5/8 (once again, only subtracting the numerators) 8/8- 5/8= 3/8 Therefore, 3/8 of the muffins are left. Hope this helps :)