Answer:
Orginal Speed is 135
Step-by-step explanation:
The ratio of final speed: original speed is

We know that 90 km is it final speed so, we set up a proportion


If you notice the picture below, the amount of fencing, or perimeter, that will be used will be 3w + 2l
now

solve for "w", to see what critical points you get, and then run a first-derivative test on them, for the minimum
notice the

so. you can pretty much skip that one, though is a valid critical point, the width can't clearly be 0
so.. check the critical points on the other
I’ve already tried to answer this question but somebody already said it was wrong I’m sorry baby