Seven more than the quotient of a number and 2 is 10

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

The? half-life of a radioactive substance is 20 years. if you start with some amount of this? substance, what fraction will remain in 120 ? years

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?