You are having a garage sale. at lowe's, a cash box cost $10 and for sale signs cost $7 each. you spent a total of $38 before taxes. how many for sale signs did you buy in addition to the cash box?

  4 signs

Step-by-step explanation:

The total amount you spent is ...

  cash box cost + sign cost = total amount

You are told the cash box costs $10, the signs are $7 each, and the total is $38. If n is the number of signs, then the total amount is ...

  $10 + $7 × n = $38

Subtracting the cost of the cash box gives the amount you spent on signs:

  7n = 28

Dividing by 7 gives the number of signs:

  28/7 = n = 4

You bought 4 signs.