Why is -7 an integer but not a natural number?

Natural Numbers are basically "counting numbers". If I ask you to start counting, you'll start at 1, then 2, then 3, and so on. It doesn't include 0 or any negative numbers because you wouldn't start from -10 when asked to count.

-7 is negative so it cannot be a natural number, but it is an integer. An integer is a whole number, this means that it does not have any decimal places or fractions. However, a natural number must be a whole non-zero number and positive. This is because natural numbers are numbers found naturally in measurements or in counting. Additionally, all natural numbers are integers but not all integers are natural numbers. For example, -3 would be an integer, 9 would be an integer and a natural number, and 7.6 would be neither.

4/6 = 2/3

so it should take 3/3 hours per man. so 9 hours is the answer 3*3 =9

step-by-step explanation:

so, converting firstly the mixed fractions to improper fractions and then "adding".