Question

The total cost of 12 pens and 5 pencil is equal to rs 111.Also,the cost of 1 pencil is rs 5 less than the cost of 1 pen .What will be the cost of 8 pens and 9 pencils?Simplification math

Answer 1

Answer:

Rs.91

Step-by-step explanation:

Let x be the cost of pen and y be the cost of pencil.

total cost of 12 pens and 5 pencil is equal to rs 111 => 12x + 5y = 111. ====> [1]

Cost of 1 pencil is rs 5 less than the cost of 1 pen => y = x-5 => x-y = 5 ====> [2]

Multiply [2] with 5 and add to [1]

12x+5y = 111

5x-5y  = 25

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17x = 136

x = 136/17 = Rs. 8

Substitute value of x in [2]

8 - y = 5 => y = Rs. 3.

Now cost of 8 pens and 9 pencils = 8x + 9y = 8*8+ 9*3 = 64+27 = Rs. 91.