<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 </span>
okay so you have to take the steps you learned in math and apply because this is actually hard and you just have to really take your time and annotate the exerpt