1) A family wants to fence in a rectangular area for a garden. One side of the garden will border their house and will not be fenced. Find the dimensions of the garden with greatest area that can be enclosed with 36. ft of fencing.

2) The amount of simple interest earned on an investment over a fixed amount of time is jointly proportional to the principle invested and the interest rate. A principle investment of $2800.00 with an interest rate of 1% earned $112.00 in simple interest. Find the amount of simple interest earned if the principle is $4900.00 and the interest rate is 2%.

3) The cost, in dollars, of filling your gas tank is directly proportional to the amount purchased. If 12 gallons of gas costs $15.00, how much would 15 gallons cost?