QUESTION IN DESCRIPTION

Question

On Monday patrick bought 10 cups of coffee and 5 doughnuts for his office at the cost of $16.50. On Tuesday, he bought 5 cups of coffee and 10 doughnuts for a total of $14.25. How much was each cup of coffee?

Answer 1

Let the price of a cup and a doughnut be x and y respectively.

then,

10x + 5y = 16.50  ------------(1)

and 5x + 10 y = 14.25 -------(2)

subtracting (2) from (1)*2 we get:

15x = 18.75

x = 1.25

So the price of each cup of coffee is $1.25