Answer:
4 signs
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.