Question

trey ordered some books online for $6 each. he paid a total of $3 for shipping. the total cost of the purchase was $75. how many books did he buy?
(a) write an equation that could be used to answer the question above. first, choose the appropriate form. then, fill in the blanks with the numbers 6, 3, and 75. let $b$ represent the number of books.
$square b + square = square$
$square b - square = square$
(b) solve the equation in part (a) to find the number of books.
$b = square$

Explanation:

Step1: Set up cost equation

Total cost = book cost + shipping.
$\$6b + \$3 = \$75$

Step2: Isolate the book cost term

Subtract 3 from both sides.
$6b = 75 - 3$
$6b = 72$

Step3: Solve for b

Divide both sides by 6.
$b = \frac{72}{6}$

Answer:

(a) $\boldsymbol{6b + 3 = 75}$
(b) $\boldsymbol{b = 12}$