Como se calcula el area de estos triángulos?

Use the elimination method to solve the systems of equations.choose the correct ordered pair. 7x+4y=39

Which equation expression the relationship between the number of boxes b and the number of cans c and the proportion is 48

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