You can state the qurstion in an other way
how many integers between 1-100 has 3 in their prime compostion or how many many numbers can be written as 3*a where a is any number
the multiplication table of 3 shows that 3*33=99
which means that highest product below 100 is 3*33
so there are 33 numbers that are divisible by three
6 (100) = 600
6 (10) = 60
14 (1) = 14
600+60+14
660+14= 674
1 whole and 1/3 is the answer
5/12 - a + 4/15
= 25/60 + 16 /60 - a
= 41/60 - a
The missing values is 41/60
