<span>60.5 milligrams per square centimeter
First, determine how many half lives have expired by dividing the time by the half-life. So:
55/20 = 2.75
That means that only 2^(-2.75) = 0.148650889 = 14.8650889% of the original substance remains. So just divide the amount remaining by 0.148650889 to get the original amount.
9 / 0.148650889 = 60.5445419
So originally, there was 60.5 milligrams per square centimeter 55 years ago.</span>
15 inches
i found it on https://answers.yahoo.com/question/index?qid=20160331230251AA3MILQ
Answer: 8
Step-by-step explanation: 12 minus 4 equals 8
The slant height, x, is 7.5 mm because you use the pythagorean formula and solve for c, since the you're solving for the hypotenuse which is the longest side.
