Desperate for the answer

if i give my sister 5 dollars, then we will have the same amount of money. if instead she gives me 8 dollars, then i'll have twice as much money as she has. how much money does she
have?

Let X = the amount you have and Y = the amount she has.

If you give her 5 you would have the same amount so you get an equation like:

X-5 = y +5

Simplify :

X – y = 5+5

X -y = 10  (Call this equation 1).

Now if she gives you $8 you will have twice as much as her, so set up the second equation:

2(y-8) = x +8

Simplify:

2y -16 = x +8

2y -x = 8 +16

2y -x = 24 (Call this equation 2).

Now add equation 1 and 2 together:

X – y = 10 + 2y -x = 24

Simplify to get y = 34

Now replace y with 34 in equation 1 to solve for x:

X -34 = 10, x = 44

You have $44 and your sister has $34

not sure but it may be b, as i said i'm not sure.