The cost of four dozen proof machine ribbons and five dozen accounting machine ribbons was Rs.160/-. If one dozen accounting machine ribbons cost Rs.20/-, what is the cost of a dozen proof machine ribbons?

Rs.15

Interview Candidate
Oct 1st, 2003
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sana

Dec 19th, 2015

Lets take proof machine as pm & accounting machine as am.
so, here 4 pm + 5 am=160
given that 1 am=Rs.20 then 5 am=20 x 5=100
substitute this in the above eqn,
now, 4 pm + 100 = 160
4 pm=160 -100
4 pm=60
1 pm=60/4=15
hence,the answer is 15