document.write( "Question 283354: At the local high school, 30% of the students in the Math Club are in the Science Club, and 80% of the students in the Science Club are in the Math Club. There are 15 students in the Science Club. How many students are in the Math Club?\r
\n" ); document.write( "\n" ); document.write( "a) 12 b) 15 c) 36 d) 40 e) 50\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "

Algebra.Com's Answer #205749 by Deina(147)\"\" \"About 
You can put this solution on YOUR website!
What do we know?
\n" ); document.write( "
  • Math Club students make up 80% (0.8) of the Science Club.
    \n" ); document.write( "
  • The Science Club has 15 members, so
    \n" ); document.write( "\"15+%2A+0.8+=+12\"

    \n" ); document.write( "
  • Science Club members make up 30% (0.3) of the Math Club.
    \n" ); document.write( "We'll let \"M\" stand for the Math Club Membership.

    \n" ); document.write( "\"0.3M+=+12\"

    \n" ); document.write( "Divide both sides by 30% (0.3):
    \n" ); document.write( "\"0.3M%2F0.3+=+15%2F0.3\"

\n" ); document.write( "M = 40 and bob's your uncle!\r
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "
\n" );