Help me to approach this questin's answer...

Asked by nitishkrnehu09 | 1st Jan, 2018, 04:06: AM

Expert Answer:

begin mathsize 16px style now space let space number space of space right space questions space be space straight x
and space number space of space wrong space questions space be space straight y
so space total space marks space scored space is space
3 straight x minus straight y
so space for space 15
3 straight x minus straight y equals 15
straight x plus straight y equals 10
solve space straight x space & space straight y space should space be space whole space numbers
only space 18 space gives space whole space numbers
straight x equals 7 space & space straight y equals 3
so space straight C presuperscript 10 subscript 7 cross times straight C presuperscript 3 subscript 3 equals 120 end style

Answered by Arun | 3rd Jan, 2018, 06:25: PM