It doesn't change because to add fractions, you need a common denominator. To find it, they multiplied 1/3 by 2 to make 2/6, to add to the 3/6.
It is 19 because of the Pythagorean theorem which states a squared plus b squared is c squared.
Answer: A
Step-by-step explanation: if not A then B if not B then C if not C then D if not D then your teacher doesn't like you.
