Dorthy has 90 books to put away. each shelf can hold 11 books. how many shelves can she fill?

For what values of the variable x is the expression square root of 7x+14+ square root of 7-x a real number?

Solve for x and y: 217x + 131y = 913; 131x + 217y = 827

Abird on top of a 200 ft bridge tower sees a man standing on the lower part of the bridge (which is 50 ft above the ground). the angle of depression from the bird is 26 ̊. how far is the man from the base of the bridge tower? with explanation and pictures .