Ace Hardware sells boxes of wrench (100) and hammers ($300). Howard ordered 40 boxes of wrenches and hammers for $8400. How many boxes of each are in the order?

Howard's order will contain 15 boxes of hammers and 39 boxes of wrenches.

Step-by-step explanation:

1. Let's review the data given to us for solving the question:

Price of box of wrenches = US$ 100

Price of box of hammers = US$ 300

Cost of the order = US$ 8,400

2. Let's find the exact amount of boxes of wrenches and hammers

Cost of the order = Price of box of wrenches * Number of boxes of wrenches + Price of box of hammers * Number of boxes of hammers

Replacing with the real values:

8,400 = 100 * 40 + 300 * Number of boxes of hammers

8,400 = 4,000 + 300 * Number of boxes of hammers

- 300 * Number of boxes of hammers = 4,000 - 8,400

- 300 * Number of boxes of hammers = - 4,400

Number of boxes of hammers = - 4,400/300 = 14.67 ≈ 15

For making a order without fractions or decimals of a box, it will contain just whole numbers, this way:

15 boxes of hammers + 39 boxes of wrenches

Cost of Howard's order = 15 * 300 + 39 * 100 = 4,500 + 3,900 = 8,400