Just putting them together not solving

Prove that 16^4-2^13-4^5 is divisible by 11.

Astudent must have an average on five test that is greater than it equal to 80% but less than 90% to receive a final grade of b. devon's greades on the first four test were 78% 62% 91% and 80% what range if grades on the fifth test would give him a b in the course? ( assuming the highest grade is 100%)

This summer the number of tourists in salem increased 4.5% from last years total of 426000. how many more tourists came to salem this summer