Question

5 pencil and 7 pens together cost 50 where as 7 pencil and 5 pens together cost 46 .find the cost of one pencil and pen .find there solutions graphically.​

Answer 1

Answer:

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

Step-by-step explanation:

cost of pencil = x

cost of pen = y

5 pencil + 7 pens = Rs. 50

5x + 7y = Rs.50

5x = 50-7y

x = 10 − 5/7y

Plug value of y which is factor of 5 to get whole number so plug y=5,10,15 we get for y = 5

x=10−5/7

y=10−7=3

for y=10

x=10−5/7

y=10−14=−4

for y = 15x = 10−5/7

y=10−21=−10

Therefore, the required points are (3,5),(−4,10),(−11,15).

Given that 7 pencils and 5 pens together cost Rs. 46

7x+5y=46

Subtract 7x both side we get

5y=46–7x

Divide by 5 we get

y=9.2–1.4x

Plug x=0,2,4 we get

for x=0

y=9.2–0=9.2

for x=2

y=9.2–2.8=6.4

forx=4

y=9.2–5.6=3.6

Therefore, the required points are (0,9.2),(2,6.4),(4,3.6).

the point of intersection is (3,5),