Saturday

January 31, 2015

January 31, 2015

Posted by **Anonymous** on Wednesday, January 16, 2013 at 11:34am.

the total cost of a pen and a pencil is Rs. 3.

if the total number of pens and pencils he purchased is7,

find the number of pens he purchased.

- maths-urgent -
**Reiny**, Wednesday, January 16, 2013 at 4:22pmlet the cost of a pen be 3x

let the cost of a pencil be 2x , ( notice 3x : 2x = 3:2 )

number of pens --- a

number of pencils --- 7-a , because their sum is 7

3x + 2x = 3

5x = 3

x = Rs 3/5 = Rs 0.6

so a pen costs Rs 1.8

and a penci costs Rs 1.2

1.8a + 1.2(7-a) = 12

1.8a + 8.4 - 1.2a = 12

.6a = 3.6

a = 6

so there were 6 pens purchased and 1 pencil

check:

1+6 = 7 , number of pens and pencils checks!

cost of pen = 1.8

cost of pencil = 1.2

ratio is 1.8 : 1.2 = 3 : 2 , ratio costs checks!

6pens + 1 pencil = 6(1.8) + 1.2 = 12

All looks good!

**Answer this Question**

**Related Questions**

mircoeconomic - Lakshani has $5 to spend on pens and pencils. Each pen costs $0....

math, help - how do i write the equations so i can solve it i will do the ...

Math - In a store, pencils have one price and pens have another. 3 Pencils and 2...

Math - A pen costs twice as much as a pencil. If Susan spends $ 1.50 for a pen ...

Math - A pen costs twice as much as a pencil. If Susan spends $ 1.50 for a pen ...

Algebra1 - Sally bought some ordinary pencils and 4 times as many special ...

Math (prealgebra) - the cost of apen is 3 times the cost of a pencil. the cost ...

MATHS LAH - Charlotte bought 46 pens and pencils. Each pen costs $6 and each ...

math - Tom has $10 that he wants to use to buy pens and pencils. However, he ...

Math - Upon examining the contents of 38 backpacks, it was found that 23 ...