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)?
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)?
If I give my brother 5 dollars, then we will
have the same amount of money. Me – 5 = Bro + 5
If instead he gives me 25 dollars, then I'll
have twice as much money as he will have. Me + 25 = 2 * (Bro – 25)
By equation 1 Me = (Bro + 10)
Substitute that value
for Me into equation 2 (Bro + 10) + 25 = 2Bro – 50
Bro + 35 = 2Bro – 50
85 = Bro
That's the answer that was asked for; i.e., my brother has 85.
But continuing, just to be thorough, that means that I have 95.
If my brother gives me 25, then I'll have 120 and he'll have 60.
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