5pencil and 7pen together cost rs.50.whereas 7penc5pen together cost rs.46find the cost of one pencil and that of one pen
Answers
let cost(in RS) of one pencil = x
and cost (in RS) of one pen = y
Therefore , according to question
5x+7y = 50 ........ (1)
7x + 5y = 46 .........(2)
Multiply equation 1 by 7 and equation by 5 we get
7(5x+7y)= 7*50
35x +49y = 350 .......(3)
and
5(7x +5y) = 5*46
35x +25y = 230 ....... (4)
Subtract equation 4 from equation 3 , we get
35x + 49y - 35x - 25y = 350 -230
49y -25y = 120
24y = 120
y = 120 /24
y= 5
Substitute y=5 in equation 1 , we get
5x + 7*5 =50
5x+35 =50
5x = 50 - 35
5x =15
x= 15/5
x=3
Hence Cost of One Pencil = x =3
Cost of One Pen =y =5
Answer:
Step-by-step explanation:
Let the cost of 1 pencil =Rs x
And cost of 1 pen = Rs y
CASE 1: 5x+7y=50.......(1)
CASE 2: 7x+5y=46....(1)
Adding equation 1 and 2
5x + 7y= 50
7x+ 5y= 46
12x+12y=96
12(x+y)=96
x+y=96/12
x+y=8........(3)
Subtracting equation 1 and 2
We get,
5 x + 7y=50
7 x + 5y =46
(-) (-) =(-)
-2x+2y=4
2(-x+y)=4
-x+y=2........(4)
From equation 3 nd 4
x+y= 8
-x+y=2
2y= 10
y=5
Puting y in equation 3
x=8- y
x=8-5
x=3
Y=5 and x=3