A machine can make 30 widgets in 8 minutes. At this constant rate, how many widgets will 4 such machines make in   hours?

Step 1: First, we need to find out how many widgets one machine can produce in one minute. We do this by dividing the total number of widgets by the total number of minutes. So, 30 widgets / 8 minutes = 3.75 widgets per minute.

Step 2: Next, we need to find out how many widgets one machine can produce in one hour. Since there are 60 minutes in an hour, we multiply the number of widgets per minute by 60. So, 3.75 widgets per minute * 60 minutes = 225 widgets per hour.

Step 3: Now, we need to find out how many widgets four machines can produce in one hour. We do this by multiplying the number of widgets per hour by the number of machines. So, 225 widgets per hour * 4 machines = 900 widgets per hour.

So, four machines can produce 900 widgets in one hour at the constant rate.