To find the percent increase, we divide the amount of change by the original number. The amount of change is the difference between the 2 numbers which in this case is 700 - 620 and the original number is 620.
[tex]So[/tex] [tex]we[/tex] [tex]have[/tex] [tex]\frac{700 - 620}{620}[/tex]
700 - 620 is 80 so we're left with [tex]\frac{80}{620}[/tex] which is 0.129.
Finally, since our problem is asking for a percent, we write 0.129 as a percent by moving the decimal point 2 places to the right to get 12.9%
So when the population of a town changes from 620 to 700, it has increased by 12.9%.
