Suppose that r varies directly with s and inversely with t, and r=2 when s=3 and t=12. what is the value of r when s=5 and t=4?

i already know the answer but i'd like to know how to find it.

What is the solution to the system of the equations? x = y - 3 x + 3y = 13

Select all the correct answers.natalie buys a new car. in the first month, the odometer on the car records 800 miles. from past experience, she expects to drive 900 miles per monthselect all the functions that can be used to find the number of miles, f(n), recorded on the odometer after n months.of(n) = 800n + 100f(n) = 9001 - 100f(n) = 900n + 800(1) = 800; }(n) = f(n - 1) + 900, for n > 2f(1) = 800; 1(n) = f(n − 1) + 100, for n > 2(1) = 900; }(n) = f(n - 1) + 800, for n > 2

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ah=4 and hc=1, find bh.