The following table represents the number of computers (numbers in thousands) manufactured by four companies from period 2014 to 2016. Study the table carefully and answer the following question.

For the years 2014 to 2016, what is the difference (numbers in thousands) between the combined production of computers by Companies A and D and the production of computers by Companies B and C taken together?

280

Production of A & D in 2014 to 2016 - Production of B & C in 2014 to 2016

= {(1350+570+420) + (810+990+580)} - {(750+520+1170) - (630+1280+650)}

= 4720 - 5000

= - 280

= 280  ( production is positive )