document.write( "Question 145688: A disc jockey must play 14 commercial spots during 1 hour of a radio show. Each commercial is either 30 seconds or 60 seconds long. If the total commercial time during 1 hours 11 minutes, how many 30-second commericals were played that hours? How many 60-second commercials? \n" ); document.write( "

Algebra.Com's Answer #106319 by stanbon(75887) $\"\"$ $\"About$

You can put this solution on YOUR website!
A disc jockey must play 14 commercial spots during 1 hour of a radio show. Each commercial is either 30 seconds or 60 seconds long. If the total commercial time during 1 hours 11 minutes, how many 30-second commericals were played that hours? How many 60-second commercials?
\n" ); document.write( "-----------------
\n" ); document.write( "Let # of 30 second spots be \"t\":
\n" ); document.write( "Let # of 60 second spots be \"s\":
\n" ); document.write( "----------------
\n" ); document.write( "EQUATIONS:
\n" ); document.write( "Quantity equation: t + s = 14
\n" ); document.write( "Time equations : 30t + 60s = 71 seconds
\n" ); document.write( "---------------------
\n" ); document.write( "t = 14-s
\n" ); document.write( "Substitute to get:
\n" ); document.write( "30(14-s)+ s = 14
\n" ); document.write( "420-29s = 14
\n" ); document.write( "29s = 406
\n" ); document.write( "s = 14 (# of sixty second spots)
\n" ); document.write( "----------------
\n" ); document.write( "Substitute into t = 14-s to get:
\n" ); document.write( "t = 14-14 = 0 (# of thirty second spots)
\n" ); document.write( "=============
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
\n" ); document.write( " \n" ); document.write( "

\n" );