Does (a+ b) +7 = a+ (7+ b)

Achemist has 200 ml of a 10% sucrose solution. she adds x ml of a 40% sucrose solution. the percent concentration, y, of the final mixture is given by the rational function: the chemist needs the concentration of the final mixture to be 30%. how many milliliters of the 40% solution should she add to the 10% solution to get this concentration?

Just tell me how to set up the equation.

Alogical argument that is presented in graphical form using boxes and arrows is called?