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)?
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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)?
Call M the amount currently held by Me
Call B the amount currently held by Brother
(M – 5) = (B + 5) (eq 1)
(M + 25) = 2 • (B – 25) (eq 2)
Multiply (2) out M + 25 = 2B – 50
Multiply both sides of (1) by 2 2M – 10 = 2B + 10
Subtract –M + 35 = – 60
Combine like terms –M = –95
Multiply both sides by –1 M = 95
Plug value of M into (1) 95 – 5 = B + 5
Combine like terms 85 = B
My Brother currently has 85 dollars
check answer
Plug 95 and 85 into (2) (95 + 25) = (2)(85 – 25)
120 = 2 • 60
120 = 120
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