Q. In the sum ⊗ + 1 ⊗ + 5 ⊗ + ⊗ ⊗ + ⊗ 1 = 1 ⊗ ⊗ for which digit does the symbol ⊗ stand?
(a) 2
(b) 3
(c) 4
(d) 5
Correct Answer: (b) 3
Question from UPSC Prelims 2020 CSAT Paper
Explanation :
x+1x+5x+xx+x1=1xx
x + 1x + 5x + xx + x1 = 1xx
=> x + 10+ x + 50 + x +10x + x + 10x + 1 = 100 + 10x + x
=> 24x + 61 = 100 + 11x
=> 13x = 39
=> x = 3
