Answer:
there are total 80 packages are on the truck.
Explanation:
weight of the car + weight of the packages = total weight when car filled
5.5 tons + x ( 0.0075 tons ) = 6.1 tons
0.0075x = 6.1 tons - 5.5 tons
0.0075x = 0.6 tons
x = ( 0.6 tons ) / ( 0.0075 )
x = 80 packages