How many Positive Integers are there between 20 to 100 exclusively? Select one:
a. 70
b. 80
c. 81
d. 79

79

Step-by-step explanation:

There is a cool easy way to solve this kind of problem. If a range is given, and the entire range increases in incrememnts of 1, then you can find the number intergers inclusive by taking the first number and subtracting it from the last and adding 1. Since in this problem you want it exclusive, we can rewrite the range to 21-99.

99-21 +1 = 78 + 1 = 79

first option

a function is a relation in which an input is paired with exactly one output.

so, let's find the right answer.

in our first option, our inputs are january, february, and march. the outputs are 30, 28, and 25. each input has it's own output. this is correct!

our second option we know is incorrect, because ms. valverade has two outputs, dogs and cats. this is not a function.

our third option is incorrect as well. the yellow square has two ouputs, the square and the triangle.

lastly, in our fourth option, we see the number 7 two times with a different output. therefore, this is not a function.

remember: each input must be paired with only one output!