Can someone please help me ​

How can we find the measure of an exterior angle if we know the measurement of an interior angle

The difference between two numbers is one. three times the larger number minus two times the smaller number is 9. what are the two numbers

Emily is entering a bicycle race for charity. her mother pledges $0.90 for every 0.75 mile she bikes. if emily bikes 18 miles, how much will her mother donate?