Remark
You need to convert 1/3 +7/24 to a common denominator. 24ths seem to be the best denominator to use.
1/3 = 8*1/3*8 = 8 / 24
Now add the two fractions together.
8/24 + 7/24 = 15/24 Both numerator and denominator can be divided by 3
15/3 = 5
25/3 = 8
So your fraction is 5/8 = 0.625