144, its just repeated addition... 12+12+12+12+12+12+12+12+12+12+12+12=144
Step-by-step explanation:
2x + 1 = 16
2x = 15 (subtract 1 on both sides)
x = 7.5 (divide 2 om both sides)
Since 7.5 is not an integer, (a) is No.
However 7.5 is rational, therefore (b) is Yes.
I think, not 100% sure, but I think it is square root (A/4pi)=r