Photo-math take a picture of your problem and it will give you your answer
X is the first number
Y is the second number
X+6 = 1/2Y
X+Y = 21
solving both equations will give you
X= 3 and Y =18
Answer:
10.98 days is 10.98/3.66 = 3 half life periods and half of the mass is lost at each half life. You can do this in your head. I have!!
Step-by-step explanation: