To finish an order in time the company had to produce 40 items daily, but it produced 20 items more daily and finished the order 3 days ahead of time. In how many days was the company supposed to finish the order?

9 days.

Step-by-step explanation:

If the company produced 20 more items than 40 items each day, then it must have produced 60 items each day.

Though you're probably expected to write an equation, it's easiest to solve this through educated guess and check.

If there were 120 items to be produced, the company would be required to do it in 3 days (120 items, 40 items/day) but completed it in 2 days (120 items, 60 items/day). In this case, they finished their order 1 day early. But the problem states that they finished 3 days early. So we guess 3 times 120 items, or 360 items. Checking this, they should have finished their order in 9 days (360 items, 40 items/day) but they finished in 6 days (360 items, 60 items/day). 6 is three less than 9, so our guess of 360 items was correct. We have shown that the company should have finished the order in 9 days.

If you had to use an equation:

Let the desired number of days be x. Then, the company finished its order in x - 3 days. Since number of items produced is the number of days times items per day, and it doesn't change:

number of items = 40 items/day * x days = 60 items/day * (x - 3) days

40x = 60 (x - 3) = 60x - 180

180 = 20x

x = 9

9 days is the desired answer.