Final answer:
There were approximately 40 million more TVs in 2015 compared to 1980.
Step-by-step explanation:
To find the number of TV's in 2015, we need to calculate the difference between the number of families with TV's in 2015 and 1980. The difference is approximately 100 million - 60 million = 40 million families. Since each family has one TV, the number of extra TV's in 2015 is also 40 million. This can be written in scientific notation as 4 x 10^7 TV's.