They have 20 pieces of 12 foot lumber. If they need 2 screws for every 3 feet of lumber, how many screws do they need?

20 * 12 = 240

240/3 = 80

2 * 80 = ?

80*2=160

To find out how many screws they need, we need to determine the total number of feet of lumber they have and then calculate the number of screws required based on that measurement.

The first step is to multiply the number of pieces of lumber (20) by the length of each piece (12 feet) to find the total number of feet of lumber.

20 pieces * 12 feet/piece = 240 feet of lumber

Next, we need to determine the number of screws required for every 3 feet of lumber. The ratio given is 2 screws per 3 feet.

To calculate the screws needed for 240 feet of lumber, we can set up a proportion and solve for x, where x represents the number of screws required.

2 screws / 3 feet = x screws / 240 feet

By cross-multiplying, we have:

2 * 240 = 3 * x
480 = 3x

Finally, divide both sides of the equation by 3 to solve for x:

480 / 3 = x
160 = x

Therefore, they will need 160 screws.