CAT Exam 2021 Slot 3 Solved Paper

Let Rahul work at a units/hr and Gautam at b units/hour
Now as per the condition :
$ 8a + 6b =7.5a + 7.5b$
so we get $0.5a=1.5\b $
or $a=3b$
Therefore total work = $8\a +6\b = 8\a +2\a =10a$
Now Rahul alone takes $ {10\a}/10 = 10 \hours$