Can somebody please help and do both problems

If f(x)=2x-6 and g(x)=3x+9, find (f-g)(x)

Idon't get undoing if its pass adding and subtracting so can someone ? x-2 over 5 = 18

Arandom sample of n = 25 observations is taken from a n(µ, σ ) population. a 95% confidence interval for µ was calculated to be (42.16, 57.84). the researcher feels that this interval is too wide. you want to reduce the interval to a width at most 12 units. a) for a confidence level of 95%, calculate the smallest sample size needed. b) for a sample size fixed at n = 25, calculate the largest confidence level 100(1 − α)% needed.