Did not solve this correctly need help

Math 3501. Fall 2022, 6 Exercise 2. Let A be a random variable with mean 20 and standard devi- ation 3. Let B be a random variable with mean 30 and standard deviation 5. Suppose Cov(A, B) = -7. Find the mean and variance of C = 4A + 3B - 100. Remember, variance is the square of standard deviation.) ( = 4(20 ) + 3 ( 30 ) - 10 0 C = 170 mean ( = 4 A + 3 B - 100 Variance 42 ( 3 ) + 32 ( 5 ) - 100 11 ( = 48 + 45 - 100 -4 C = - Anotsure about this calculation ( = 4 ( 3 2 ) + 3 (5 2 ) C - 1 11 T use