<span>if isabel runs 7 miles in 50 minutes, then you know she runs 7/50 miles in one minute, right? So multiply that by the number of minutes she did run, and you can find the distance:
</span><span> 7
------ x 75 =
50
525
------
50
</span><span> If you plug that fraction into your calculator, you get 10.5, so 10 and a half miles.</span>
<1, 1, 1> × <1, 0, 1> = <1, 0, -1>
The cross product of the normals of the planes gives the direction vector of their line of intersection.
The rates are equivalent because both of them do 30 jumping jacks a minute.
