400. Just add a zero when you're dealing with tens
7.1 is ten times smaller than 71
Answer:
9/35
all the boxes in one row are 7 and the number of rows are 5 .. so 7x5=35 and the number of boxes shaded are 9
Let d = number of dimes, q = number of quarters
<span>Sally has 20 coins in her piggy bank, so </span>
<span>d + q = 20 </span>
<span>The total amount of money is $3.05. </span>
<span>Use the value of each coin multiplied by its number to get total value </span>
<span>.10d + .25q = 3.05 </span>
<span>multiply everything by 100 to clear the decimal places </span>
<span>10d + 25q = 305 and </span>
<span>d + q = 20 </span>
<span>solve the second equation above in terms of either d or q - lets do d </span>
<span>d = 20 - q </span>
<span>sub that into the first equation </span>
<span>10d + 25q = 305 </span>
<span>10(20 - q) + 25q = 305 </span>
<span>200 - 10q + 25q = 305 </span>
<span>15q = 105 </span>
<span>q = 105/15 = 7 </span>
<span>and from above </span>
<span>d = 20 - q = 20 - 7 = 13 </span>
<span>so, there are 13 dimes and 7 quarters </span>
<span>verify with orig problem </span>
<span>13 + 7 = 20, OK, and $1.30 + $1.75 = $3.05
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