Calculating power factor with RLC in series

[anderssok09]

How would I calculate power factor based off of this question?

In a AC 120V 60HZ circuit with a RLC in series calculate the power factor given Xc-3 XL=7 and R=4.

The answer is 0.70, but I don't know how to come up with the answer

[rofo42]

How would I calculate power factor based off of this question?

In a AC 120V 60HZ circuit with a RLC in series calculate the power factor given Xc-3 XL=7 and R=4.

The answer is 0.70, but I don't know how to come up with the answer

Z = Square root of R²+ (X_L - X_C)²

Z = 4² + (7 - 3)² = 5.656

COS = R / Z

4 / 5.65 = .707