What equation is described below?

42 is 2 times as many as 21

Possible Answers:
21×2=42

42×2=21

42×2=21

21×2=42

42÷2=21

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