How do you work out the length of radius and diameter of these two circles?

So for the first one what you did was wrong as in wrong formula.
Radius is 5cm as it is given and diameter is double the radius which is 10.
So r=5
And D=10.

For the second one the diameter is 16cm as it is given and radius is half the diameter,so half of 16 is 8cm right?
So r=8
And D=16

Cbecause they are equal so that means it is the same on both sides? ! hope this