The amount of money spent world-wide for streaming music services t years after 2010 can be approximated by:
m(t)= 0.42t + 0.532,
where m(t) is in billions of dollars. determine (using an inequality) those years for which more than $3 billion will be spent for streaming music services.

Because we need that m(t) is greater than $3 billion we simply write:
0.42t + 0.532 > 3

Now we proceed to solving:
0.42t > 2.468
t > 2.468/0.42
t> 5.876

If we want to make t as integer that means that from 2016 (6 years after 2010) more than $3 billion will be spent for streaming music services

In this problem it decreased 20%