You would do 20 • 3=60 and the you would add 20 • 1/5=4 so, your total is 64in.
Y = t*e^(-t/2)
y' = t' [e^(-t/2)] + t [e^(-t/2)]' = e^(-t/2) + t[e^(-t/2)][-1/2]=
y' = [e^(-t/2)] [1 - t/2] = (1/2)[e^(-t/2)] [2 - t] = - (1/2) [e^-t/2)] [t -2]
To solve, divide the dollars by the pounds of peanuts to find the cost per pound:
12/8 =1.5
So, it cost $1.50 per pound of peanuts.
Hope this helps!
