5n+15 as an undistributed expression

In need of in the diagram, ∠abc is a right angle. ∠dbc = 30°27'40". find the measure of ∠abd.

Weekly wages at a certain factory are normally distributed with a mean of $400 and a standard deviation of $50. find the probability that a worker selected at random makes between $450 and $500

The expression 1.01*1.005(^t) gives the amount of money, in thousands of dollars, in carter's savings account (t) years after he opens it. what does 1.01 represent in this expression?