The doubling time of a city's population is 21 years. how long does it take for the population to quadruple?

When eating out, record the total cost of your meal (before tip) and the tip that you left. determine the percent of the cost of the meal that you left as a tip.

What is the factored form of the following expressions? d^2 – 13d + 36

If the segment op is dilated by a scale factor r=2, what is the length of segment op? a)10cm b)16cm c)6cm d)4cm