15x-10=20
+10 +10
15x=30
\15 /15
x=2
you add 10 to both -10 (they cancek eachother out) and 20 (equals 30)
Then you divide 30 by 15 (equals 2) and 15 by 15 (they cancel eachother out)
Then you get x=2
Work from the left to right.
add 1/4 and 1/2 which would give you 3/4
then subtract 3/4 from both sides of the equal sign witch would give you
x=-3/2
The formula for the standard error is this:
σM = σ / √N
where
σM is the standard error
σ is the standard deviation
N is the number of samples
So,
σM = 0.45 / √50
σM = 0.0636 or 6.36%
The standard error is 0.0636
