System of equations

Question

hardcover books are four dollars each and paperback books are 2 dollars each. A person spends $26 for 8 books how many hardcover books did she purchase 

Answer 1

Let h = the number of hardcover books and s = the number of softcover books purchased

 

s + h = 8

s = 8 - h

 

$26 = $4.00*h + $2.00*s

26 = 4h + 2s

 

Substitute 8-h in place of s:

26 = 4h + 2(8-h)

26 = 4h + 16 - 2h

10 = 2h

5 = h

 

s = 8 - h

s = 6 - 5

s = 3

 

Check:

$26 = $4.00*h + $2.00*s

$26 = ($4)*5 + ($2)*3

$26 = $20 + $6

$26 = $26

Check!