1/2 + 1/8
To be able to add the two fractions you need to make the denominators (the numbers on the bottom of the two fractions) the same. So in this case the easiest thing to do is to make the denominator 8 for both fractions.
So, 1/2 + 1/8 = (1/2)x(4/4) + 1/8
And so now, 1/2 + 1/8 = (1x4)/(2x4) + 1/8 = 4/8 + 1/8
(can you see that 4/8 is actually the same thing as 1/2? So we’ve not actually changed the fraction, just made it easier to deal with in this context)
And 4/8 + 1/8 = (4 +1)/8 = 5/8