What is the slope of the line in the graph

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

Isabelle is mixing red and blue paint to make purple paint she adds 3/10 of a fluid ounce of red to 12/25 of a fluid ounce of blue to make 1 1/30 fluid ounces of purple how many fluid ounces of red paint ounces of red paint will she need to make 3 fluid ounces of purple paint

Iknow the square root of 2 is irrational