What is the sum of the first 100 positive integers

To determine the number of deer in a forest a forest ranger tags 280 and releases them back

How many liters of peroxide should be added to 12 liters of an 8% peroxide solution so that the resulting solution contains 16% peroxide?   original added new amount of peroxide 0.96 liters x 0.96 + x amount of solution 12 liters x 12 + x 0.18 liter 1.14 liters 1.92 liters 2.10 liters

Can anyone me get through my algebra 2 class? the only class i need to graduate..