Maria can fill a certain order in 13 hours and Jim needs 15 hours to do the same job. Working together, how long will it take them to fill the order?

7 hours

Step-by-step explanation:

Maria can fill a certain order in 13 hours,

so her working rate is

and Jim needs 15 hours to do the same job, so his working rate is:

Assuming the two will take x hours working together, then

It will take both approximately 7 hour

ik how do do this just give me a few minutes and i will give it to

option (b) is correct

step-by-step explanation:

to find the solution of this system, we need to convert it into reduced row-echelon form. we have,

after applying row operations r2 -> r2/2 and r3 -> r3/3, we get,