Alright, so the population of the herd is 220 in 2012. This means that when it decreased by 10 percent in 2014, 10 percent of the population is taken away. To find 10 percent of the population, we simply multiply 220 by 0.1 due to that to get a percentage as a decimal, we simply divide the percentage amount by 100. In addition, as the elk population in 2012 represents 100% of the elk population that we’re starting with (100%=1, or the whole thing), 10% subtracted from 100% is 90% of the population, or 220*0.9 as the population in 2013. To get the population in 2014, we have to multiply the population in 2013 by 0.9 similar to how we got from 2012 to 2013. This means we multiply (220*0.9)*0.9=178.2, which rounds down to 178 as the next number, 2, is less than 5. If that 2 were to be 5 or higher, we would round up to 179.
So a triangle is always 180°. If one angle is 90° then we can subtract that from the 180° to find out how much the other two will be. 180°-90°=90° So the other two angles added together will have to equal 90°.
