Question 1208627
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Answer: <font color=red>$73</font>


Explanation


x = amount of money you start with
y = amount of money your brother starts with


Giving your brother $8 will decrease your amount to x-8. 
Meanwhile his amount will increase to y+8.
At this point the two amounts are equal.
x-8 = y+8
x-8-8 = y
<font color=blue>y = x-16</font>
We'll substitute this into another equation. 


If instead your brother gives you $19, then your amount increases to x+19 and his amount drops to y-19.
At this point your amount is twice that of his.
your amount = 2*(his amount)
x+19 = 2*(y-19)
x+19 = 2*(<font color=blue>x-16</font>-19) ....... plug in <font color=blue>y = x-16</font>
x+19 = 2*(x-35)
x+19 = 2x-70
x-2x = -70-19
-x = -89
x = 89 dollars is what you started with.


y = x-16
y = 89-16
y = <font color=red>73 dollars</font> is what your brother started with.


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Check:


If you give him $8, then<pre>your amount = 89-8 = 81
his amount = 73+8 = 81</pre>Showing you both would end up with the same amount of money ($81)
This verifies the first condition.


If he gives you $19, then <pre>your amount = 89+19 = 108
his amount = 73-19 = 54</pre>Notice that 108 is twice that of 54
54*2 = 108
Both conditions have been verified.
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