The population of dolphins in the Pacific Ocean in 1990 was 243,000. It is decreasing every year by 2.3% due to pollution in our oceans. If this trend continues, how many dolphins will be there in 2030?

Year 1990, dolphins were 243,000
2.3% of 24300
= ( 2.3 / 100 ) * 243000
= ( 0.023 ) * 243000
= 5589
So every year, the population of dolphins decrease by 5589.

Now from 1990 to 2030 will be
= 2030 - 1990
= 40 years

Therefore, for a year = 5589 decrease
For forty years, it will be
= 40 * (5589)
= 223560 dolphins will be lost after forty years

The remaining ones
= 243000 - 223560
= 19440 dolphins will be left