First, write the mixed number as a sum of a whole number and a proper fraction. Then write the two parts with common denominator , and add. Once you're used to this, you can use a shortcut method: 1) Multiply the whole part by the denominator of the fractional part, and add the numerator of the fractional part.
P = 2(L + W)
P = 22
L = 2W - 4
22 = 2(2W - 4 + W)
22 = 2(3W - 4)
22 = 6W - 8
22 + 8 = 6W
30 = 6W
30/6 = W
5 = W.....width is 5 cm
L = 2W - 4
L = 2(5) - 4
L = 10 - 4
L = 6....length is 6 cm
No, because the hypotenuse needs to be three. It would be true if the lengths were 2, 2, 4