Mean 60 - 2(0.9) = 58.2
58.2 is 2 standard deviations from the mean.
- - Let's solve for C.
Starting off with our equation:

Transform:

Solve for that:

Solve for that for the last time and your answer is
You could use a simple calculator it's only 10.
It’s d, looks like you got it already! With ratios, just pay attention to not only the numbers but order of the words as well, so you can be sure the ratio follows the problem.
2x-4=49
2x=54
x is equal to 27