Answer: he bought 5 cups of coffee.
He bought 3 cups of hit chocolate
Step-by-step explanation:
Let x represent the number cups of coffee that he bought.
Let y represent the the number cups of of hit chocolate that he bought.
He bought a total of 8 cups coffee and hit chocolate. This means that
x + y = 8
Each cup of coffee costs $2.25 and each cup of hit chocolate costs $1.50. If he pays a total of $15.75 for 8 cups, it means that
2.25x + 1.5y = 15.75 - - - - - - - - - - - - 1
Substituting x = 8 - y into equation 1, it becomes
2.25(8 - y) + 1.5y = 15.75
18 - 2.25y + 1.5y = 15.75
- 2.25y + 1.5y = 15.75 - 18
- 0.75y = - 2.25
y = - 2.25/- 0.75
y = 3
Substituting y = 3 into x = 8 - y, it becomes
x = 8 - 3 = 5
