yan is running on a track that is of a km long. she can run 4 laps in 12
minutes. what is her speed in km per minute?

3 km per minute

Step-by-step explanation:

12/4=3 laps

3 km per minute

the answer is 844

step-by-step explanation:

it is 844 because if you add 836.50 + 7.5 you will get 844

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4