The rate at which a baby bird gains weight is proportional to the difference between its adult weight and its current weight. At time t=0 , when the bird is first weighed, its weight is 20 grams. If B(t) is the weight of the bird, in grams, at time t days after it is first weighed, then
dtdB=51(100−B).
Let y=B(t) be the solution to the differential equation above with initial condition B(0)=20 .