document.write( "Question 693143: mark has twice as many quarters as nickles and 3 more dimes than nickles, he has $4.20 in all, how many of each does he have. we need formula to figure this out, my daughter is having horrible time with this, and it has been to long for me to remember. \n" ); document.write( "

Algebra.Com's Answer #427302 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let $\"+n+\"$ = the number of nickels he has
\n" ); document.write( "Let $\"+d+\"$ = the number of dimes he has
\n" ); document.write( "Let $\"+q+\"$ = the number of quarters he has
\n" ); document.write( "given:
\n" ); document.write( "(1) $\"+q+=+2n+\"$
\n" ); document.write( "(2) $\"+d+=+n+%2B+3+\"$
\n" ); document.write( "(3) $\"+5n+%2B+10d+%2B+25q+=+420+\"$
\n" ); document.write( "( the units for this equation is cents , for instance,
\n" ); document.write( "$4.20 is 420 cents )
\n" ); document.write( "------------------------
\n" ); document.write( "At this point it is important to know if you have
\n" ); document.write( "enough information to arrive at a solution.
\n" ); document.write( "There are 3 unknowns and 3 equations, which
\n" ); document.write( "means a solution is possible.
\n" ); document.write( "-------------------------
\n" ); document.write( "All you have to do is substitute (1) and (2) into (3)
\n" ); document.write( "so that the only variable is $\"+n+\"$ , then solve
\n" ); document.write( "(3) $\"+5n+%2B+10%2A%28+n+%2B+3+%29+%2B+25%2A%282n%29+=+420+\"$
\n" ); document.write( "(3) $\"+5n+%2B+10n+%2B+30+%2B+50n+=+420+\"$
\n" ); document.write( "(3) $\"+65n+%2B+30+=+420+\"$
\n" ); document.write( "Subtract $\"+30+\"$ from both sides
\n" ); document.write( "(3) $\"+65n+=+390+\"$
\n" ); document.write( "(3) $\"+n+=+6+\"$
\n" ); document.write( "-------------
\n" ); document.write( "And, since
\n" ); document.write( "(2) $\"+d+=+n+%2B+3+\"$
\n" ); document.write( "(2) $\"+d+=+6+%2B+3+\"$
\n" ); document.write( "(2) $\"+d+=+9+\"$
\n" ); document.write( "-------------
\n" ); document.write( "Also, since
\n" ); document.write( "(1) $\"+q+=+2n+\"$
\n" ); document.write( "(1) $\"+q+=+2%2A6+\"$
\n" ); document.write( "(1) $\"+q+=+12+\"$
\n" ); document.write( "-------------
\n" ); document.write( "Mark has 6 nickels, 9 dimes, and 12 quarters
\n" ); document.write( "-------------
\n" ); document.write( "check answer:
\n" ); document.write( "(3) $\"+5n+%2B+10d+%2B+25q+=+420+\"$
\n" ); document.write( "(3) $\"+5%2A6+%2B+10%2A9+%2B+25%2A12+=+420+\"$
\n" ); document.write( "(3) $\"+30+%2B+90+%2B+300+=+420+\"$
\n" ); document.write( "(3) $\"+420+=+420+\"$
\n" ); document.write( "OK
\n" ); document.write( "(1) $\"+q+=+2n+\"$
\n" ); document.write( "(1) $\"+12+=+2%2A6+\"$
\n" ); document.write( "(1) $\"+12+=+12+\"$
\n" ); document.write( "OK
\n" ); document.write( "(2) $\"+d+=+n+%2B+3+\"$
\n" ); document.write( "(2) $\"+9+=+6+%2B+3+\"$
\n" ); document.write( "(2) $\"+9+=+9+\"$
\n" ); document.write( "OK
\n" ); document.write( "Hope this helps\r
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