In the figure shown, all the resistors have the same resistance. If the ideal ammeter reads 2 A and the ideal voltmeter reads 15V, what is the resistance of each resistor?

Twice the current flows through the single resistor as through each of the resistors in
parallel. Therefore, 2/3 of the total potential drop of 15V appears across the single resistor, and 1/3, or 5V, appears across each parallel resistor. Since the current through one parallel resistor is 2A, its resistance must be (5V) /(2A) $=\frac{5}{2}\mathrm{\Omega }$