Question

Sam buys 27 pencils 31 erasers at
jack buys 31 pencils and 27 erasers for ruppes 89 Write a linear equation
to model this situation if cost
of one pencil is
ruppes x and eraser is y and also find the cost of each pencil and eraser
​

Answer 1

Answer:

Form the pair of linear equations in the following problems, and find their solution graphically:

(i) 10 students of class X took part in Mathematics quiz. If the numbers of girls is 4 more than the number of boys, find the number of boys and girls who took part in the quiz.

(ii) 5 pencils and 7 pens together cost Rs. 50, whereas 7 pencils and 5 pens together cost Rs. 46. Find he cost of one pencil and a pen.

(iii) Champa went to a 'sale' to purchase some pants and skirts. When her friends asked her how many of each she had bought, she answered, "The number of skirts is two less than twice the number of pants purchased. Also, the number of skirts is four less than four times the number of pants purchased." Help her friends to find how many pants and skirts Champa bought.

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ANSWER

(i)

Total of 10 students took part in the quiz,

number of girls + number of boys =10

x+y=10.....(1)

number of girls is 4 more than boys,

number of girls = 4+ number of boys

x=y+4

x−y=4......(2)

solving (1) and (2), we get,

x=7

y=3

Number of girls =7

Number of boys =3

(ii)

Let the cost of one pencil be x

let the cost of one pen be y

5x+7y=50.......(1)

7x+5y=46.........(2)

solving (1) and (2), we get,

x=3

y=5

cost of pencil =3

cost of pen =5

(iii)

Number of skirts purchased = 2 * number of pants purchased -2

⇒y=2x−2

2x−y=2........(1)

Number of skirts purchased = 4 * number of pants purchased -4

⇒y=4x−4

4x−y=4........(2)

solving (1) and (2), we get,

x=1

y=0

Number of pants purchased =1

Number of skirts purchased =0

• Hope it helps
• By Subechha Datta

Answer 2

Answer:

one pencil cost = x

so 27 pencils is of = 27 ×X =27x

same as 31 pencils = 31x

same as cost of one ruber is = y

so cost of 31 rubers= 31y

same as 27 erasers = 27y

so the equation is

27x +31y = 89

31x +27y = 89

now cross multipication

multiple first digit of each row with other row

31 ( 27x +31y = 89)

27 ( 31x + 27y =89)

837x + 961y = 2759

837x + 729y = 2403

- - - ( now equate equations by changing the signs of second equation )

0x + 132y = 356

y = 356/ 132

y = 269

Now put this value in any equation

and you will get value of x

Step-by-step explanation:

I hope may be this easy explanation help you