Number of people < (should be smaller than or equal to but I don't have that button on my keyboard) (100-7) / 15.50
103/15.50 = 6.64516...
You can't have .645 of a person, so you must round down. Therefore, she can bring 6 people including herself.
The formula is
R=I/pt
R interest rate?
I interest earned 150
P principle 2000
T time 3 years
R=150÷(2,000×3)
R=0.025 × 100
R=2.5%
Hope it helps!