We have the equation:

so:

and:

This equation has one solution.
1/10 of all take 2/5 time
10/10=10 times 1/10
so 10 times 2/5 time=20/5=4 days to finish 1 order
4 days
This would be a lot easier with the figure.
Four equal spaces means quarters.
A is 1 mark to the left of 0, so 1/4 to the left of 0. That's -1/4
Answer: Negative one-fourth