Suppose 1 and 2 are true mean stopping distances at 50 mph for cars of a certain

Question:

Suppose µ1 and µ2 are true mean stopping distances at 50 mph for cars of a certain type equipped with two different types of braking systems. Use the two-sample t test at significance level .01 to test H0: µ1 - µ2 < -10 versus Ha: µ1 - µ2 < -10 for the following data:
M = 6 , = 115.7, s1 = 5.03, n = 6, = 129.3, and s2 = 5.38.