Answer:
11 days
Step-by-step explanation:
380-160=220
20 times 11 =220
answer 11 days
Since D=MV, we can infer that M=D/V
That is your equation----------------^
It's closed under addition. You can take any two natural numbers you want, add them up and you'll get some other natural number (eg: 3 and 5 ---> 3+5 = 8)
it's not closed under subtraction. Sure 5-3 = 2 is a natural number but 3-5 = -2 is not a natural number
so that leads us to the answer being choice B
