Alright, since it decreases by 0.9 each year, the amount it decreases in x years = 0.9*x. We need to find out how long it takes to decrease 85-35=50 percent, so 0.9*x=50. Dividing both sides by 0.9, we get x=around 56 (we rounded up from 55+ something). Since we start at 1969, we get our end time to be
1969+56 (since we rounded up) to get 2025. We add the 2 up because it takes 56 years to change
