1/4 + 1/2 ..you cant directly add them as they are unlike fractions ..so to add then first convert them into like fractions ...for that find the LCM of the denominators ..2 and 4 ..
LCM of 2 and 4 is .. 4
so 1/4 + 1/2 will become 1/4 + 2/4 ...(because we multiplied 1/2 with 2 to make denominator as 4)
=> the answer is 3/4 ..
this is how i do ..
Hope it helps !!!