First you have to figure out n. Let's say it's 1, then you would multiply it by 4. That would be 4. Then subtract 32. In this case, then the answer would be - 28.
For this one, first you have to figure out w. Let's make w = 2. Then multiply is by 3 so it would be 6. Then add 66. In this case, it would be 72.
if there are 10 girls and 6 boys total we have 16 students. Divide 10 by 16 which give 62% a girl will be picked and for boys divide 6 by 16 which is 38% a boy will be picked.