If goods be purchased for Rs.840 and one-fourth be sold at a loss of 20% at what gain percent should the remainder be sold so as to gain 20% on the whole transaction?

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If goods be purchased for Rs.840 and one-fourth be sold at a loss of 20% at what gain percent should the remainder be sold so as to gain 20% on the whole transaction?

A. 30%
B. 33%
C. 33 1/3%
D. 35%
Explanation:
1/4 CP = 210 SP = 21*(80/100) = 168
SP = 840*(120/100) = 1008
1008 – 168 = 840
3/4 SP = 630
Gain = 210
630 — 210
100 — ? => 33 1/3%