If you add km/ hr with another km/ hr what will you get​

km/hr

Explanation:

Addition and subtraction are commutative

Meaning you can add or subtract in any order because it doesn't change the sum or the difference. So it doesn't change the units.

km/ hr + km/ hr =(km+ km)/hr=2km/hr

Explanation:

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =