Can anyone ?
in 2000, the world population was 6 billion. if the world population is growing at a rate of 1.4% per year, predict the population in 2010? in 2075? and

Haruka hiked several kilometers in the morning. she hiked only 66 kilometers in the afternoon, which was 25% less than she had hiked in the morning. how many kilometers did haruka hike in all?

Which geometric principle is used to justify the construction below?

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )