While Michelle sat observing birds at a bird feeder, one fourth of the birds flew away when they were startled by a noise. Two birds left the feeder to go to another stationed a few feet away. Three more birds flew into the branches of a nearby tree. Four birds remained at the feeder. How many birds were at the feeder initially?
Four birds remain at the end. So, start reversing the process.
4+3 = 7
7+2 = 9
x/4 = 9 (Because 1/4 flew away)
9*4=36
x=36, or 36 birds were there originally.
We can then verify that is correct.
36/4=9
9-2=7
7-3=4