If I give my brother 5 dollars, then we will have the same amount of money. If instead he gives me 25 dollars, then I'll have twice as much money as he will have. How much money does my brother currently have (in dollars)?
So for this question,x will be your starting amount and y will be your brothers.
So both the following equations are true.
x-5 = y+5
2(y-25) = x+25
First we will start with the 2nd equation 2(y-25) = x+25
Firstly,we will do 2y=x+75, which will get us y=1/2x+37.5.
Now we do the first equation which is x-5=y+5, which will give us x=y+10 and plug both into the old equation,which will give us:
y = 1/2(y+10) + 37.5
y = 1/2y+5+37.5
y = 1/2y + 42.5
1/2y = 42.5
y = 85
So logically, X should equal 95
The answer is 85.