Do you use the same principle when adding and subtracting as you would multiplying in fractions?

No that wouldn't work.
e.g 1/2 + 1/2 would become 2/4 (which is equivalent to 1/2) if you just added the numbers, which can't be right.

You need to find equivalent fractions so that each fraction has the same number on the bottom (denominator) and then add ( or take away) the top numbers.

1/2 + 1/2 has same number on bottom, so just add top numbers to get 2/2 =1

so 1/4 + 1/2 has diff nos on bottom, so change 1/2 to 2/4.
1/4 + 2/4 = 3/4

2/3 - 1/4 = 8/12 - 3/12 = 5/12

You may need to ask your teacher about equivalent fractions.

Your answer is no hope i helped good luck with your homework

Idon't know what's the answer lol