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Let, he had red pens at first = x
Hence, blue pens at first = 180 - x
After, gave away,
red pens = x - x * 40/100 = 6x/10
blue pens = (180 - x) - (180 - x) * 10/100
Now, 6x/10 = 162 - 9x/10 + 48
6x/10 = 162 - 9x/10 = 210
x = (210 * 10)/15 = 140
Hence, at first he had red pens = 140