Maria walked 3 km west and 4 km south . calculate how far she is from her starting point.

If you draw her track and connect her starting and ending points, you have a right triangle, with 3 and 4 being the legs. According to the pythagorean theorem. 3^2+4^2=x^2 when x is her distance from starting point. so x^2=25 and x=5. Her distance is 5

3x+9+4x+x=8x+9that's the answer for your question.