Please help! Trying to figure out how to do this two problems!

You give a $4 tip for a meal that cost $22. approximately what percent of the bill was your tip?

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

This is a map of the mars exploration rover opportunity predicted landing site on mars. the scale is 1cm : 9.4km. what are the approximate measures of the actual length and width of the ellipse? i mostly need to know how to set it up : )