X value must have only one value in order to get a function.
So the answer is the first choice.
20 is the lowest of the upper 3 numbers, so the missing number must be 19 when averaged with 20. That is, the missing number must be ...
2*19 -20 = 18
1.a
2.d
3. they all are the same type of number, real rationals
4. No irrational number is a rational number
5.No irrational number is a integer
Let wind speed = x mph
when she rode 2 miles against the wind we have:-
speed = distance / time so
20 - x = 2 / t -------(1) where t is the time she took.
when riding with the wind we have
20 + x = 3 / t--------(2) adding equations (1) and (2):-
40 = 2/t + 3/t
40 = 5/t
t = 5/40 = 1/8 hr
x = 20 - 2 / 1/8 = 20 - 16 = 4
Wind speed was 4 mph Answer