$6.25 is the cost of 5 lbs. of apples. Here the question is 'what is the
cost of 1 lb of apple?' To find the unit rate or the cost of 1 lb of
apple, divide the sum by the given quantity. The sum is @6.25 and the
given quantity is 5 lbs. So the unit rate = 6.25/5 = $1.25
