What's equation of the best fit for the graph

Afactory adds 3 red drops and 2 blue drops of coloring to white paint to make each pint of purple paint. the factory will make 50 gallons of the purple paint.how many drops of red and blue coloring will the factory need in the 50 gallon batch of purple paint.

Im literally having a mental breakdown

Write the expression 7x^3-28xy^2 as the product of 3 factors