*see the attachment below showing Lewis' work
Answer:
*He simplified √400 incorrectly. It should be 20 instead of 200.
*He found the difference between the hypotenuse and the short leg instead of the long leg
Explanation:
=>Going through the work of Lewis, you'd observe that in the 5th line where Lewis was supposed to simplify √400, he made a mistake by writing 200 instead of 20. The square root of 400 is 20 not 200.
=>Also, the length of the longest leg of the right angled triangle that Lewis is supposed to subtract from the length of the hypothenuse is 16 NOT 12.
The difference between the length of the hypothenuse and the length of the longest Leg = 20 - 16 = 4