The answer is 0.04 its that easy
Circumference of entire circle = 2 * PI * 10
circumference of entire circle =
<span>
<span>
<span>
62.832 feet
81 degrees is (9/40) of a circle
62.832 * </span></span></span><span>(9/40) = </span>
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<span>
<span>
14.1372
</span>
</span>
</span>
Source:
http://www.1728.org/radians.htm
19 × 1.03 = 19.57
The answer is 19.57.
recalling that d = rt, distance = rate * time.
we know Hector is going at 12 mph, and he has already covered 18 miles, how long has he been biking already?

so Hector has been biking for those 18 miles for 3/2 of an hour, namely and hour and a half already.
then Wanda kicks in, rolling like a lightning at 16mph.
let's say the "meet" at the same distance "d" at "t" hours after Wanda entered, so that means that Wanda has been traveling for "t" hours, but Hector has been traveling for "t + (3/2)" because he had been biking before Wanda.
the distance both have travelled is the same "d" miles, reason why they "meet", same distance.
![\bf \begin{array}{lcccl} &\stackrel{miles}{distance}&\stackrel{mph}{rate}&\stackrel{hours}{time}\\ \cline{2-4}&\\ Hector&d&12&t+\frac{3}{2}\\[1em] Wanda&d&16&t \end{array}\qquad \implies \begin{cases} \boxed{d}=(12)\left( t+\frac{3}{2} \right)\\[1em] d=(16)(t) \end{cases}](https://tex.z-dn.net/?f=%5Cbf%20%5Cbegin%7Barray%7D%7Blcccl%7D%20%26%5Cstackrel%7Bmiles%7D%7Bdistance%7D%26%5Cstackrel%7Bmph%7D%7Brate%7D%26%5Cstackrel%7Bhours%7D%7Btime%7D%5C%5C%20%5Ccline%7B2-4%7D%26%5C%5C%20Hector%26d%2612%26t%2B%5Cfrac%7B3%7D%7B2%7D%5C%5C%5B1em%5D%20Wanda%26d%2616%26t%20%5Cend%7Barray%7D%5Cqquad%20%5Cimplies%20%5Cbegin%7Bcases%7D%20%5Cboxed%7Bd%7D%3D%2812%29%5Cleft%28%20t%2B%5Cfrac%7B3%7D%7B2%7D%20%5Cright%29%5C%5C%5B1em%5D%20d%3D%2816%29%28t%29%20%5Cend%7Bcases%7D)

Here are some formulas...
percent increase = (new number - original number) / original number...* 100
percent decrease = (original number - new number) / original number...* 100
============
a student raises her grade from a 75 to a 90....since it is going from a smaller number to a larger number, u have an increase
percent increase = (90 - 75) / 70....* 100
= 15/70 * 100
= 0.2142 * 100
= 21.42 rounds to 21.4% increase
-------------------------
36.50 on sale for 32.12...since it goes from a larger number to a smaller number, u have a decrease
percent decrease = (original number - new number) / original * 100
= (36.50 - 32.12) / 32.12...* 100
= 4.38 / 32.12...* 100
= 0.1363...* 100
= 13.63 rounds to 13.6% decrease
------------------------------
23.5 to 21.2......this is a decrease
percent decrease = (original number - new number) / original...* 100
= (23.5 - 21.2) / 23.5....* 100
= 2.3 / 23.5....* 100
= 0.0979 * 100
= 9.79 rounds to 9.8% decrease