Answer:the cost of a box of donut is $3.55
Step-by-step explanation:
Let x represent the cost of a box of donut.
Let y represent the cost a chocolate pie.
Rainy bought a box of donuts and a chocolate pie. They cost $8.80 all together. This means that
x + y = 8.80 - - - - - - - - - - - 1
The chocolate pie cost $1.70 more than the box of donuts. This means that
y = x + 1.70
Substituting y = x + 1.70 into equation 1, it becomes
x + x + 1.7 = 8.80
2x + 1.7 = 8.8
2x = 8.8 - 1.7 = 7.1
x = 7.1/2 = 3.55
y = x + 1.70 = 3.55 + 1.7 = 5.25
