Isaac drove at an average speed of 54 mph over six hours. During the first three hours he drove at a speed that was 187 mph less than four times the speed he averaged for the last three hours. How fast did he drive during the first three hours?
since distance = speed * time,
If his speed for the last three hours was x, then
3(4x-187) + 3x = 54*6
To find out how fast Isaac drove during the first three hours, we need to first calculate his average speed for the last three hours. We know his average speed over six hours was 54 mph. Therefore, to find the average speed for the last three hours, we divide the total distance traveled in those three hours by three.
Since the average speed for six hours was 54 mph, we multiply 54 by 6 to get the total distance traveled, which is 324 miles.
Let's represent the speed during the first three hours as "x." We are given that his speed during the first three hours was 187 mph less than four times the speed for the last three hours.
So, the equation we can write is: x = 4(54) - 187
Now, let's solve the equation:
x = 216 - 187
x = 29
Therefore, Isaac drove at a speed of 29 mph during the first three hours.