The price of oranges went from $.90 per lb to $1.20 per lb in five years. find the rate of change of the price of oranges.
a) $0.30 per pound per year
b) $0.06 per pound per year
c) $0.24 per pound per year
d) $0.18 per pound per year

Rate is an expression for a change of some unit per unit of time. For this problem, we find the rate of change of the price by a simple equation which is expressed as: 

Rate = change in price / change in time
Rate = ($1.20/lb - $0.90/lb) / 5 yrs - 0
Rate = $0.06 per lb per year

Thus, the answer is B.

Bis the answer! hope this