ivy bought 10 packs of cups for her holiday party. a pack of medium cups costs $1.80 and a pack of large cups costs $2.40. she paid a total of $21.60. how many packs of each size cup did she buy?

Respuesta :

Answer:

4 packs of medium cups and 6 packs of large cups

Step-by-step explanation:

1.80x + 2.40y = 21.60

1.80(4) + 2.40(6) = 21.60

7.2 + 14.4 = 21.60

21.60 = 21.60

Answer:

Ivy bought 4 packs of medium cups, and 6 packs of large cups.

Step-by-step explanation:

To solve this problem, we will have to use a system of equations. Our first equation will represent the cups, and our second equation the costs.

Let [tex]m[/tex] equal medium cups.

Let [tex]l[/tex] equal large cups.

[tex]m+l=10[/tex]

[tex]1.80m+2.40l=21.60[/tex]

Let's use substitution to solve this system.

Subtract [tex]l[/tex] from both sides of the first equation:

[tex]m=10-l[/tex]

Let's substitute [tex]10-l[/tex] into the second equation for [tex]m[/tex]:

[tex]1.80(10-l)+2.40l=21.60[/tex]

Distribute [tex]1.80[/tex] into [tex](10-l)[/tex]:

[tex]18-1.80l+2.40l=21.60[/tex]

Combine like terms:

[tex]18+0.6l=21.60[/tex]

Subtract [tex]18[/tex] from both sides of the equation:

[tex]-0.6l=3.60[/tex]

Divide by the coefficient of [tex]l[/tex], which is [tex]0.6[/tex]:

[tex]l=6[/tex]

Ivy bought 6 packs of large cups.

_

Let's substitute [tex]6[/tex] into the first equation to find the number of medium cup packs:

[tex]m+6=10[/tex]

Subtract [tex]6[/tex] from both sides of the equation:

[tex]m=4[/tex]

Ivy bought 4 packs of medium cups.

_

We can check our work 2 ways; by substituting our solved values into the initial equations.

1st Equation Check:

[tex](4)+(6)=10[/tex]

[tex]10=10[/tex]

2nd Equation Check:

[tex]1.80(4)+2.40(6)=21.60[/tex]

[tex]7.2+14.4=21.60[/tex]

[tex]21.60=21.60[/tex]

Our answers are correct!