Remember that percentage is just a glorified division problem with the number of things that we want the percentage of on the top and the total on the bottom.
This question is asking about the percentage of left handed sixth graders. So we need to know (1) how many left handed sixth graders there are and (2) how many total sixth graders there are.
The problem states that there are 9 girls and 3 boys that are left handed. To get the total, we add.
9 girls + 3 boys = 12 students that are left handed.
The problem also states that there are 90 girls and 60 boys total in the sixth grade. To get this total, we also add.
90 girls + 60 boys = 150 students
Now, we can calculate the percentage.
We take the 12 lefties and divide that by the 150 total sixth graders. When we get a decimal, we multiply by 100 to get the percentage.
So
12/150 = 0.08
0.08 x 100 = 8%
