![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
Original: 21 hours \ \
\New: 40 hours
\Since the new hours is greater than the original, this is a percent of increase.
\The amount of change = New hours – Original hours.
\The amount of change = ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=c84229d0e1c9db0e463d436db980098d.png\")
.![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step2.JPG\")
Let r be the percentage of increase.
\Use the original number, 21 as the base.
\The percent proportion is ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=7c3502283b849cf70e03318c917835b8.png\")
![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step3.JPG\")
To solve for r, first find the cross products.
\![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=b19b17d6c4007010bb4fb6266ce38701.png\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=808847d9f1f2c7388ef8034b976cc3c8.png\")
Divide each side by 21.
\![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=672e226776ddce621bc428d071f78f1f.png\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=6e443dee490ea8a21cf9b631ae0980d6.png\")
The percentage of increase is above 94%.![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")
The percent of change is a percent of increase.The percentage of increase is above 94%.