The time taken by operator A to finish a task has a normal distribution with a mean

Question:

The time taken by operator A to finish a task has a normal with a mean 220 minutes and a standard deviation 11 minutes. The time taken by operator B to finish a task has a normal with a mean 185 minutes and a standard deviation 9 minutes, independent of operator A. Operator A began working at 9 A.M. The probability that operator A finishes before operator B is 0.90. What time did operator B start working?
Distribution
The word "distribution" has several meanings in the financial world, most of them pertaining to the payment of assets from a fund, account, or individual security to an investor or beneficiary. Retirement account distributions are among the most...