Consider the circuit shown in (figure 1). assume i = 0.96 a.

Current Through 10 ohm Resistance I = 0.96 A so voltage difference Across 10 ohm resistance V = IR = 0.96 times 10 ohm = 9.6 v As the three resistance are in parallel then P.D across all the resistance is 9.6 v therefore current Through 15 ohm resistance I_2 = 9.6/15 = 0.64 A So current through the resistance R - I_3 = 2 - (I + I_2) = 2 - (0.96 + 0.64) = 0.4 A therefore From ohm's law V = I_3 R implies R = 9.6/0.4 = 24 ohm therefore value of R is 24 ohm