Can you help me with math homework? (7th grade)

Amanda and Rick have the same amount to spend on school supplies. Amanda buys 4 notebooks and has $8.60 left. Rick buys 7 notebooks and has $7.55 left. How much does each notebook cost?

For Rick:

X - 7N = 7.55 [the original amount minus 7 notebooks is $7.55]

For Amanda:

X - 4N = 8.60 [the original amount minus 4 notebooks is $8.60]

Subtract the first equation from the second:

X - 4N = 8.60
-(X - 7N = 7.55)
----------------------
3N = 1.05

Divide both sides by 3:

N = 1.05 / 3 = 0.35

Notebooks cost 35 cents each.

Notice that Rick buys 7 - 4 = 3 more notebooks than Amanda, and that Rick spends $8.60 - $7.55 = $1.05 more than Amanda. From this fact, we see that the three extra books cost Rick $1.05. Assuming each notebook costs the same amount, we can just divide $1.05 by 3 to get the required cost of each notebook to be $1.05/3 = $0.35.

I hope this helps!

Difference in their money=8.60-7.55=1.05
Difference in their notebooks=7-4=3

cost of each notebook=1.05/3=0.35

4x + 8.60 = y

7x + 7.55 = y

7x + 7.55 = 4x + 8.60

3x + 7.55 = 8.60

3x = 1.05

x = 0.35

I hope this information was very helpful.