How can you check your answer when you are adding or subtracting fractions

You can check your answer with subtracting by adding the answer by either of the fractions you subtracted. For adding, you subtract the sum by one of the numbers you added. Hope I helped :)

You just have to do the opposite. So if you do 5+4=9 and you are not sure that is correct then you would do 9-5=4 or 9-4=5 if you get all of the same numbers that are in the question then it is right. It goes the same for fractions. I hope I helped.

If you need an equation, it would be y=2x+8, y would be how long it grew, x being weeks.if you need how long he was asleep, it would be 4 weeks if he started with no beard, the equation would be x=8÷2if he did have a beard before hand, the equation would be 2w+x=8