In order to simplify a fraction, we have to find a common factor in both numerator and denominator. So, let's start by factor the expressions completely: at the numerator we have

At the denominator we have

So, the fraction can be written as

You can see that there is a factor
in common, that can be simplified:

The circumference is pi times the diameter of the circle. The radius is half of the diameter. In this case, the radius is then 36.
0.43 =
3/100 = 0.03
+
4/10 = 0.4
0.03 + 0.4 = 0.43.
Hope this helped☺☺