A 16.0 Ω, 13.0 Ω, and 7.00 Ω resistor are connected in parallel to an emf source. A current of 6.00 A is in the 13.0 Ω resistor. Calculate the equivalent resistance of the circuit. Answer in units of Ω.

The current in one parallel resistor doesn't tell us the equivalent resistance of the circuit. And the equivalent resistance of the circuit doesn't depend on the current through any of the resistors, or the voltage applied to them, or even whether there IS any current through any of them.  

Resistors in parallel have the same equivalent resistance even if they're wrapped in tissue, placed in a matchbox, and stored in the back of a drawer in a desk and locked in a dusty warehouse.

The equivalent resistance of 16Ω, 13Ω, and 7Ω all in parallel is the reciprocal of

(1/16) + (1/13) + (1/7) .

That's  1 / (0.0625 + 0.0769 + 0.1429)

That's  1 / (0.2823)

That's   3.543 Ω .

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