What angle is supplementary to 120 degrees

Can someone check if i did this correct. it’s number 4 if you’re wondering.

The map shows the location of the airport and a warehouse in a city. though not displayed on the map, there is also a factory 112 miles due north of the warehouse.a truck traveled from the warehouse to the airport and then to the factory. what is the total number of miles the truck traveled?

Find the percent error of the measurement 4 cm