document.write( "Question 823316: Currently, my father's age is four times the total age of my sister and me, but eight years from now, it will be only double. Also, in three years, my age will be twice my sister's age. What is the current age of my father, my sister, and me? \n" ); document.write( "
Algebra.Com's Answer #495416 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
f = father's present age; b = brother's age; s = sisters age
\n" ); document.write( ":
\n" ); document.write( "Currently, my father's age is four times the total age of my sister and me,
\n" ); document.write( "f = 4(b + s)
\n" ); document.write( "f = 4b + 4s
\n" ); document.write( ":
\n" ); document.write( "but eight years from now, it will be only double.
\n" ); document.write( "f + 8 = 2(b+8 + s+8)
\n" ); document.write( "f + 8 = 2(b+s+16)
\n" ); document.write( "f + 8 = 2b + 2s + 32
\n" ); document.write( "f = 2b + 2s + 32 - 8
\n" ); document.write( "f = 2b + 2s + 24
\n" ); document.write( "f = f so we can write it
\n" ); document.write( "4b + 4s = 2b + 2s + 24
\n" ); document.write( "combine like terms
\n" ); document.write( "2b + 2s = 24
\n" ); document.write( ":
\n" ); document.write( " Also, in three years, my age will be twice my sister's age.
\n" ); document.write( "b + 3 = 2(s+3)
\n" ); document.write( "b + 2 = 2s + 6
\n" ); document.write( "b = 2s + 6 - 3
\n" ); document.write( "b = 2s + 3
\n" ); document.write( "b - 2s = 3
\n" ); document.write( "Use elimination with these two equations
\n" ); document.write( "2b + 2s = 24
\n" ); document.write( " b - 2s = 3
\n" ); document.write( "--------------adding eliminates s find b
\n" ); document.write( "3b = 27
\n" ); document.write( "b = 27/3
\n" ); document.write( "b = 9 yrs is the brothers age
\n" ); document.write( "find s using 2b + 2s = 24
\n" ); document.write( "2(9) + 2s = 24
\n" ); document.write( "2s = 24 - 18
\n" ); document.write( "2s = 6
\n" ); document.write( "s = 3 yrs is sisters age
\n" ); document.write( "then
\n" ); document.write( "f = 4(9 + 3)
\n" ); document.write( "f = 48 yrs is dad's age
\n" ); document.write( ":
\n" ); document.write( " :
\n" ); document.write( "Check solutions in the statement:
\n" ); document.write( "\"eight years from now, it will be only double.
\n" ); document.write( "48 + 8 = 2(9+8 + 3+8)
\n" ); document.write( "56 = 2(17+11)
\n" ); document.write( "56 = 2(28) \n" ); document.write( "
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