PLEASE HELP ME! Solve: system by elimination form

1.
2x + y = 25
3y = 2x - 13

Which three lengths could be the lengths of the sides of a triangle? 21 cm, 7 cm, 7 cm 9 cm, 15 cm, 22 cm 13 cm, 5 cm, 18 cm 8 cm, 23 cm, 11 cm

You are at a restaurant and owe $38 for your meal. you want to leave a 20% tip. how much will your tip be?

Sketch the region enclosed by the given curves. decide whether to integrate with respect to x or y. draw a typical approximating rectangle and label its height and width. y= 5x, y=7x^2then find the area s of the region.