What ordered pairs are the solutions of the system of equations shown in the graph below?

Angles r and s are complementary. the measure of angle r is 31 degrees. which equation can be used to find angle s?

Me d is also an option but i couldn't get it in the picture

How many liters of peroxide should be added to 12 liters of an 8% peroxide solution so that the resulting solution contains 16% peroxide?   original added new amount of peroxide 0.96 liters x 0.96 + x amount of solution 12 liters x 12 + x 0.18 liter 1.14 liters 1.92 liters 2.10 liters