Two tugboats pull a disabled supertanker. Each tug exerts a constant force of 2.10×10^6 N , one at an angle 15.0 degree west of north, and the other at an angle 15.0degree east of north, as they pull the tanker a distance 0.780 km toward the north. A) What is the total work done by the two tugboats on the supertanker?