Please see pic, I'd solved in it.
I believe it's 9.1 Hope this helps :)
The correct answer of the given question above would be option d and option b. The conversion factors that should be used to convert 4km/min are 60 minutes is to 1 hour and 1 kilometer is to 1000 meters. Therefore, in 4km/min, there are 4000m in every 0.0167 min. Hope this answer is able to help you.
Subtract the 2 equations
7x+2y=-19
- -x+2y = 21
--------------------------
8x +0y=-2
x= -1/4
