Step 1. Simplify 10/3b to 10b/3
12/5(10b/3 + 15/4)
Step 2. Distribute
8b + 9
9 students
30% ends up being .3%, multiply .3% by 30 students which equals 9.
The length can be found using the Pythagorean Theorem...
c^2=a^2+b^2 and in this case:
d^2=(dx^2)+(dy^2)
d^2=(3-7)^2+(12-9)^2
d^2=-4^2+3^2
d^2=16+9
d^2=25
d=5
So the length of AB=5 units.
