document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=614316>Question 614316</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The ratio of a boy’s age to his father’s age is 1 : 4. In 4 years’ time, the ratio of their ages will<BR>\n" );
document.write( "be 1 : 3. How old is the boy now? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #386487 by </B><A HREF=/tutors/aboutme.mpl?userid=mananth><B>mananth(16946)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mananth><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=mananth><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=386487\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> boy's age  be x<BR>\n" );
document.write( "and father's age =y<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%2Fy+=+1%2F4 ALIGN=MIDDLE  ALT=\"x%2Fy+=+1%2F4\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "so y= 4x<BR>\n" );
document.write( "In 4 years their ages will be<BR>\n" );
document.write( "x+4 & y+4\r<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28x%2B4%29%2F%28y%2B4%29+=+1%2F3 ALIGN=MIDDLE  ALT=\"%28x%2B4%29%2F%28y%2B4%29+=+1%2F3\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "cross multiply<BR>\n" );
document.write( "3(x+4) = (y+4)<BR>\n" );
document.write( "substitute y \r<BR>\n" );
document.write( "\n" );
document.write( "3x+12=4x+4<BR>\n" );
document.write( "4x-3x=12-4<BR>\n" );
document.write( "x=8 the boy's age\r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );