G7. how many strings of eight upper case english letters are there a) if letters can be repeated? b) if no letter can be repeated? c) that start with x, if letters can be repeated? d) that start with x, if no letters can be repeated? e) that start and end with x, if letters can be repeated? f) that start with letters bo(in that order), if letters can be repeated? g) that start or end with letters bo(in that order) if letters can be repeated?

Grace is standing 18 feet from a lighthouse and kelly is standing 10 feet from grace. the angle that grace looks up to see the top of the lighthouse is 45°. the angle that kelly looks up to see the top of the lighthouse is y°. find the height, h, of the lighthouse. find the angle, rounded to the nearest tenth of a degree, in which kelly looks up to the top of the lighthouse. to the nearest tenth of a degree, find the value of x° . in two or more sentences, explain your calculations