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Siri bought 2 notebooks and 3 pens for Rs 90 . Lakshmi bought

4 notebooks and 5 pens for Rs 140. Form linear equations

Question

Siri bought 2 notebooks and 3 pens for Rs 90 . Lakshmi bought

4 notebooks and 5 pens for Rs 140. Form linear equations for the given

situation to find the cost of a pen and a notebook

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Mathematics
3 months
2021-07-21T02:22:51+00:00
2021-07-21T02:22:51+00:00 2 Answers
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## Answers ( )

taking the number of notebooks as x and pens as y

(2x+3y=90)×5

(4x+5y=140)×-3

⬇️

10x+15y=450

-12x-15y=-420

———————-

-2x=30

X=30÷-2= $-15 price of notebooks

substituting the value of x in eq 1

2x+3y=90

2(-15)+3y=90

-30+3y=90

3y=90+30

y=120÷3

=$40 is the price of no pens

I tried but hope this helps!

Answer:let the cost of one copy and one pen be x and y

As per question

2x + 3y = 90 (i)

4x + 5y = 150 (ii)

by substitution method we get

x = 90 -3y ÷ 2 iii

put equation iii in ii we get

4(90-3y÷2) + 5y =150

360-12y÷2 +5y =150

360 -12y +10y = 300

360 -2y = 300

-2y =-60

y =60÷2

y = 30 iv

put equation iv in eq i

2x + 3(30) =90

2x+90 = 90

2x = 90-90

2x = 0

x= 2