can anyone help me?! see out of 100 students who appeared in grade 8 exam of united gurkha school,60 studenrs passed mathematics,50 science and 20 in both subjects. how many students failed in both subjects ?​

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