Question

the total resistance is an electrical circuit consisting of three heater elements is 14.7 ohms.the resistance of two heater elements are 5.57 ohms and 4.91 ohms. find the resistance of the third heater element.

Answer 1

We need to know whether all three are in series, all three are
in parallel, or one is in series with the parallel combination of
the other two.

If one is in series with the other two in parallel, then we need
to know the positions of the 5.57 ohms and the 4.91 ohms. 

The answer is different for each of those cases, and I'm not
about to sit here and work out all the possible answers, for
5 points.