Question

the cost of 5 pens and 7 pencils is ed. 50.which of the following equation.a)5x/7x=50 b) 5x+7x=50 c) 5x*7x=50 d) 5x-7x=50​

Answer 1

Step-by-step explanation:

5x +7y =50

let cost of pen be x and pencil be y

for 5 pens cost= 5x

7 pencils cost=7y

total cost =50

5x+7y=50

Answer 2

Question

Answers

Related Questions

5 pencils and 7 pens together cost Rs. 50, whereas 7 pencils and 5 pens together cost Rs. 46. Find the cost of one pencil and that one pen by graphical method.

A. Cost of one pencil = Rs. 2 and that of one pen = Rs. 4

B. Cost of one pencil = Rs. 3 and that of one pen = Rs. 5

C. Cost of one pencil = Rs. 5 and that of one pen = Rs. 6

D. Cost of one pencil = Rs. 2 and that of one pen = Rs. 6

Hint: In this question use the given information to make the equations and remember to take the cost of pencil and pen as x and y respectively. Then by using the given information in the question, we will get two equations in terms of x and y. We just need to solve the equations by the graphical method to get the value of x and y.

Complete step-by-step answer:

According to the given information 5 pencils and 7 pens together cost Rs. 50

So let x be the cost of 1 pencil and y is the cost of 1 pen therefore the equation formed by the above equation is 5x + 7y = 50

⇒⇒5x = 50 – 7y

⇒⇒x = 50−7y550−7y5

⇒⇒x = 10−7y510−7y5 (equation 1)

Putting the value of y = 5, 10, 15

Substituting the values of y in equation 1

For y = 5

x = 10−7×5510−7×55

⇒⇒x = 10 – 7

⇒⇒x = 3

Now for y = 10

x = 10−7×10510−7×105

⇒⇒x = 10 – 14

⇒⇒x = – 4

Now for y = 15

x = 10−7×15510−7×155

⇒⇒ x = 10 – 21

⇒⇒ x = – 11

So the required points are (3, 5), (-4, 10), (-11, 15)

Now by the given information the cost of 7 pencils and 5 pens together is Rs. 4