Answer: 75
work: n/5 + -6 = 9
n/5 = 9+ 6
n/5 = 15
n = 15 x 5
n= 75
Answer:
> a<-rnorm(20,50,6)
> a
[1] 51.72213 53.09989 59.89221 32.44023 47.59386 33.59892 47.26718 55.61510 47.95505 48.19296 54.46905
[12] 45.78072 57.30045 57.91624 50.83297 52.61790 62.07713 53.75661 49.34651 53.01501
Then we can find the mean and the standard deviation with the following formulas:
> mean(a)
[1] 50.72451
> sqrt(var(a))
[1] 7.470221
Step-by-step explanation:
For this case first we need to create the sample of size 20 for the following distribution:

And we can use the following code: rnorm(20,50,6) and we got this output:
> a<-rnorm(20,50,6)
> a
[1] 51.72213 53.09989 59.89221 32.44023 47.59386 33.59892 47.26718 55.61510 47.95505 48.19296 54.46905
[12] 45.78072 57.30045 57.91624 50.83297 52.61790 62.07713 53.75661 49.34651 53.01501
Then we can find the mean and the standard deviation with the following formulas:
> mean(a)
[1] 50.72451
> sqrt(var(a))
[1] 7.470221
2x + 3y + 2(x - y) - 3x
First you apply the distributive property:
2x +3y + 2(x) - 2(y) - 3x
2x + 3y +2x - 2y - 3x
The you combine like terms:
2x + 2x - 3x +3y - 2y
4x - 3x + y
x (x could also be 1x) + y (y could also be 1y)
The answer is x + y or 1x + 1y