document.write( "Question 561108: The ratio of the ages of John and Janet is 3:4. In four years time the ratio of their ages will be 4:5. Find their present ages? \n" ); document.write( "
Algebra.Com's Answer #364188 by Maths68(1474)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "Let
\n" ); document.write( "Present age of John = j
\n" ); document.write( "Present age of Janet = t
\n" ); document.write( "The ratio of the ages of John and Janet is 3:4
\n" ); document.write( "j:t=3:4
\n" ); document.write( "j/t=3/4
\n" ); document.write( "j=3t/4...........(1)
\n" ); document.write( "In four years time
\n" ); document.write( "John will be = j+4
\n" ); document.write( "Janet will be = t+4
\n" ); document.write( "Then
\n" ); document.write( "the ratio of their ages will be 4:5
\n" ); document.write( "(j+4):(t+4)=4:5
\n" ); document.write( "(j+4)/(t+4)=4/5
\n" ); document.write( "5(j+4)=4(t+4)
\n" ); document.write( "5j+20=4t+16
\n" ); document.write( "5j=4t+16-20
\n" ); document.write( "5j=4t-4.............(2)
\n" ); document.write( "Put the value of j from (1) to (2)
\n" ); document.write( "5(3t/4)=4t-4
\n" ); document.write( "15t/4=4t-4
\n" ); document.write( "15t=4(4t-4)
\n" ); document.write( "15t=16t-16
\n" ); document.write( "15t-16t=-16
\n" ); document.write( "-t=-16
\n" ); document.write( "Multiply by -1 both sides of above equation
\n" ); document.write( "t=16
\n" ); document.write( "Put the value of t in (1)
\n" ); document.write( "j=3t/4...........(1)
\n" ); document.write( "j=3(16)/4
\n" ); document.write( "j=3*4
\n" ); document.write( "j=12\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Present age of John = j = 12 years old
\n" ); document.write( "Present age of Janet = t = 16 years old\r
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