Answer:
Acording to the question,
Cost per cup = $1.29
Total number of cups = 12
Total cost of cups = 12 x 1.2 = $15.48
Cost of candies = $2.49 per cup
Total number of candies = x
Cost of nuts = $0.69 per cup
Total number of nuts = y
Equations :
x + y = 12 (because total cups of nuts and candies will be equal to 12)
2.49x + 0.69y = 15.48 (Total cost of the 12 cups should be 15.48)
Step 1 : Find x in terms of y
x = 12 - y
Step 2 : substitute x in terms of y from step 1 in the second equation
2.49x + 0.69y = 15.48
2.49 ( 12 - y) + 0.69y = 15.48
29.88 - 2.49y + 0.69y = 15.48
-1.8y = -14.4
y = 14.4/1.8
y = 8
Step 3 : Find x
x + y = 12
x = 12 - y
x = 12- 8
x = 4
Thus,Yumi should use 4 cups of candies and 8 cups of nuts.