Question 1205497
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(a) 25% of the 880 cards were football cards, so 75% of them were basketball cards.  The difference between 75% and 25% is 50%, so the difference between the number of basketball cards and the number of football cards was 50% of the total number of cards.<br>
ANSWER: 50% of 880, or 440<br>
OR....<br>
25% of 880 is 220, so the number of football cards was 220 and the number of basketball cards was 880-220 = 660; the difference between 660 and 220 is 440.<br>
ANSWER (again...!): 440<br>
(b) Let x be the additional number of football cards.  The number of football cards is now 220+x; the total number of cards is now 880+x.<br>
Danny wants the total number of football cards to be 45% of the total number of cards:<br>
{{{(220+x)/(880+x)=0.45}}}
{{{0.45(880+x)=220+x}}}
{{{396+0.45x=220+x}}}
{{{176=0.55x}}}
{{{x=176/0.55=320}}}<br>
ANSWER: 320<br>
CHECK:
220+320 = 540
880+320 = 1200
540/1200 = 0.45<br>