### Video Transcript

A box contains trays of melons. There are 15 melons in a tray and three trays in a box. A supermarket sells 40 boxes of melons. How many melons does the supermarket sell?

The question tells us that there are 15 melons in a tray. And there’re three trays in a box. So one box is equal to three trays or three multiplied by 15 because there’re 15 melons in each tray. So one box contains 45 melons.

We know the supermarket sells 40 boxes. So to calculate how many melons there are in 40 boxes, we need to multiply 45 by 40. We know that 45 multiplied by 10 is 450. And since 40 is four times bigger than 10, we need to multiply 450 by four. Double 450 is 900. If we double that again, that gives us 450 multiplied by four, which is 1800.

The supermarket sells 1800 melons.

To calculate the answer, we worked out that each box contained 45 melons. There’re three trays in a box. Each tray contains 15 melons. Three times 15 is 45. The supermarket sold 40 boxes. So we multiplied 45 of the amount in one box by 40. First, we multiplied 45 by 10. And then, we multiplied the answer by four to give us a total of 1800 melons.