If you add Hillary to the friend count, that's 24. So there are 16 boys and 8 girls
8-10=-2
-2+5=3
3+7=10
10-(-20)=-10
Final score is -10 points
We can use a rule of three simple, direct proportion to solve this problem.
15 pounds correspond to $1.80, then the question is to find the price of one pound, the called unit rate. We state the rule of three:
15 pound ----> $1.80
1 pound -----> x
x = (1)(1.80)/15
x = 0.12
Therefore, each pound costs $0.12 that is the unit rate in pounds