To solve:
Every two days, the cow increases by 6lbs.
To find the unit rate, divide 6 by 2 to find the increase in weight per day.
Unit rate increase: 3lbs
To find the weight on the third day, add 3lbs onto day 2's weight.
85+3=88
Answer: A) The calf's weight is 88lbs on the third day.
