1 Estimate the difference in the loads of two​ 18-wheeler trucks. One truck has a load of 39,843 pounds and the other truck has a load of 51,763 pounds. 2 First, estimate the answer using front end rounding. Then find the exact answer. There are​ 43,560 square feet in an acre. How many square feet are there in ​acres. 3 Estimate the answer using front end rounding. Then give the exact answer. A supply house purchases 3 wheelchairs at ​$ 1376 each and 18 speech compression​ recorder-players at ​$ 738 each. Find the total cost. 4