Question

A customer at a bakery paid $78.30 for donuts and cupcakes. Each donut cost $1.95 and each cupcake cost $2.85. If they bought a total of 30 donuts and cupcakes, how many donuts did they buy?​

Answer 1

`x+y = 30` (1)

`1.95x+ 2.85y = 78.30` (2)

From equation (1) we can solve for x and we got:

`x = 30-y` (3)

Replacing (3) into (2) we got:

`1.95(30-y) +2.85 y = 78.30`

And solving for y we got:

`58.5 -1.95 y +2.85 y = 78.30`

`0.9 y = 19.8`

`y = 22`

And then solving for x we got:

`x = 30-22 = 8`

So then we have 8 donuts and 22 cupcakes

Explanation:

Let x the number of donuts and y the number of cupcakes, from the info given we can set up the following equations:

`x+y = 30` (1)

`1.95x+ 2.85y = 78.30` (2)

From equation (1) we can solve for x and we got:

`x = 30-y` (3)

Replacing (3) into (2) we got:

`1.95(30-y) +2.85 y = 78.30`

And solving for y we got:

`58.5 -1.95 y +2.85 y = 78.30`

`0.9 y = 19.8`

`y = 22`

And then solving for x we got:

`x = 30-22 = 8`

So then we have 8 donuts and 22 cupcakes