What is the slope of the line 3y = 5x + 7

15 single-crust apple pies were sold and 21 double-crust cherry pies were sold.

Step-by-step explanation:

Let a be the number of single-crust apple pies sold

Let c be the number of double-crust cherry pies sold

First, we need to write the two equations that are going on here:

We don't know the number of each pies sold, but we know 36 were sold, so we write this:

a

+

c

=

36

We also know that the price of a single-crust apple pie is $6.99 and the price of a double-crust cherry pie is $10.99. We know the money collected was $331.64, so our second equation is this:

6.99

a

+

10.99

c

=

331.64

So our two equations are:

a

+

c

=

36

and

6.99

a

+

10.88

c

=

331.64

For the first equation, let's solve for a for now.

#a = 36 - c

Now, we can plug this value of a into the other equation  

6.99

a

+

10.88

c

=

331.64

, so we have this:

6.99

(

36

−

c

)

+

10.88

c

=

331.64

(plug in value for a)

And now we continue solving:

251.64

−

6.99

c

+

10.88

c

=

331.64

(distribute)

251.64

+

3.89

c

=

331.64

3.89

c

=

80

(put variables on left of equation, put numbers on right of equation)

c

=

20.565552

...

≈

21

(rounded up to 21 because you can't sell a  

1

56

th's pieces of a pie.

Now we plug this value of c that we just solved back into the equation  

a

=

36

−

c

in order to find a. Now we solve for a:

a

=

36

−

21

(plug in the value of c)

a

=

15

So, now we know how many pieces of each were sold.

Final 15 single-crust apple pies were sold and 21 double-crust cherry pies were sold.