document.write( "Question 252188: Crystallina spent her entire $ 20 weekly allowance on books and candy last week. This week she did the same, but she spent 50 % more on candy and 12.5 % less on books.How much did she spend on candy this week? \n" ); document.write( "

Algebra.Com's Answer #183973 by drk(1908) $\"\"$ $\"About$

You can put this solution on YOUR website!
This question requires you to set up a system of equations. Let B = books, and C = candy.
\n" ); document.write( "The first sentence becomes: 20 = B + C. \r
\n" ); document.write( "\n" ); document.write( "50% more than means 100% last week + 50% this week or 150%, which is 3/2
\n" ); document.write( "12.5% less than means 100% last week - 12.5% this week or 87.5% which is 7/8.
\n" ); document.write( "The second sentence becomes: 20 = (7/8)B + (3/2)C\r
\n" ); document.write( "\n" ); document.write( "multiplying the second equation by 8, we get: 160 = 7B + 12C.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now we have
\n" ); document.write( "20 = B + C
\n" ); document.write( "160 = 7B + 12C\r
\n" ); document.write( "\n" ); document.write( "step 1 - multiply the first equation by -7. This gives us\r
\n" ); document.write( "\n" ); document.write( "-140 = -7B -7C
\n" ); document.write( "160 = 7B + 12C\r
\n" ); document.write( "\n" ); document.write( "step 2 - add down to get\r
\n" ); document.write( "\n" ); document.write( "20 = 5C\r
\n" ); document.write( "\n" ); document.write( "step 3 - solve for C. C = 4. She spent $4 on candy LAST week. This week, it was $6. \n" ); document.write( "

\n" );