33
7 girls wore mask so 7
15-9 is how many boys wore mask so 6
7+6= 13
20+ 13 is 33
If you take 1/2 of a pizza and divide it up between 6 people, will you have more than 1 whole Pizza or less than 1 whole pizza?
If you divide up a fraction into smaller pieces it will always be less than 1 because it started out less than 1 and you're making it even smaller.
2/3 of a right triangle is 60 degrees. Then x + (x+20) + 60 = 180 total.
2x + 80 = 180, so 2x = 100 and x = 50. The angles are 50, 70 and 60 (degrees)
What do you mean by "grades?"
