The diameter is just twice the radius so once we find that we will just multiply it by 2.
Circumference = 2 x

x radius
We just plug in from here.
74 = 2

r
Divide by 2

to isolate the r
74 / 2

= r
Leave it as is, because we are not done, we want an exact answer.
As said, we must now multiply by 2 because the diameter is TWICE the radius.
Diameter =

The 2 on the outside and the 2 in the denominator cancel out giving you diameter =

or diameter ≈ 23.5549 cm