Question

Rachel works at a bookstore. On Tuesday, she sold twice as many books as she did on Monday. On Wednesday, she sold 6 fewer books than she did on Tuesday. During the three days Rachel sold 19 books. Create an equation that can be used to find m, the number of books Rachel sold on Monday.
Fill this in ________ -- __________ = _________

Answer 1

Answer with Step-by-step explanation:

Let m be the number of books Rachel sold on Monday.

On Tuesday, she sold twice as many books as she did on Monday.

i.e. On Tuesday she sold 2m books

On Wednesday, she sold 6 fewer books than she did on Tuesday.

i.e. On Wednesday she sold 2m-6 books

During the three days Rachel sold 19 books.

i.e. m+2m+2m-6=19

i.e.  5m-6=19

Adding both sides by 6, we get

5m=25

Dividing both sides by 5, we get

m=5

Hence, equation that can be used to find m is:

m+2m+2m-6=19

Answer 2

Let m = the amount books Rachel sold on Monday.
then t = the amount books Rachel sold on Tuesday.
then w = the amount books Rachel sold on Wednesday.

On Tuesday she sold twice as she did on Monday.
 t = m * 2

On Wednesday she sold 6 fewer books than she did on Tuesday
w = t - 6

Now for the fun.

t = m * 2
w = t - 6

Substitute t for real value

w = m * 2 - 6

Now solve for m.

w - 6 = m * 2 <-- Transpose the 6
(w-6)/2 = m <-- Transpose the 2.
m = (w-2)/2 < The Law of Reflexive Property of Equality