at joes cafe, one cup of coffee and three doughnuts cost $3.50, and two cups of coffee and two doughnuts cost $3.80. what is the cost of one doughnut

Answer 1

Let the cost of one cup of coffee be C and the cost of one doughnut be D.

From the information given, we can set up a system of equations:
C + 3D = 3.50 (equation 1)
2C + 2D = 3.80 (equation 2)

To simplify equation 2, we can divide it by 2:
C + D = 1.90 (equation 3)

Now we have a system of equations with 2 variables.

We can solve equation 3 for C:
C = 1.90 - D

Substituting this into equation 1, we get:
(1.90 - D) + 3D = 3.50
1.90 + 2D = 3.50
2D = 3.50 - 1.90
2D = 1.60
D = 1.60/2
D = 0.80

Therefore, the cost of one doughnut is $0.80.