Me solve using either elimination or comparison.

ms. audet bought 20 basketballs for a total of $700. if the practice balls cost $30 and the official balls used for games cost $50, how many of each did she buy?

Adj has a total of 1075 dance and rock songs on her system. the dance selection is 4 times the size of the rock selection. write a system of equations to represent the situation.

Koji is installing a rectangular window in an office building. the window is 823 feet wide and 534 feet high. the formula for the area of a rectangle is a=bh. what is the area of the window? enter your answer as a mixed number in simplest form in the box. $$ ft2

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?