Question

Plz help me solve this question ASAP without using algebra, Thank u‼️

Answer 1

Let cost of 1 box of red pen = x

Let cost of 1 box of black pen = y

Gaga bought 5 red box and her sister 4 black box then total cost is given by

5x+4y

Given that total cost was $44

so equation will be 5x+4y=44...(i)

After exchange

Gaga= 4 red box + 1 Black box

Sister = 1 red box + 3 Black box

then cost for Gaga = 4x+1y

cost for sister = 1x+3y

Given that cost for both after exchange is same so we get

4x+1y = 1x+3y

or 4x-1x = 3y-1y

or 3x = 2y

or 3x/2=y ...(ii)

plug (ii) into (i)

5x+4y=44

5x+4(3x/2)=44

5x+12x/2=44

5x+6x=44

11x=44

x=4

Now plug value of x into (ii)

y=3x/2=3*4/2=12/2=6

Hence cost of 1 box of red pen = $4

And cost of 1 box of black pen = $6

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If you want to get solution without solving both equations then just graph both equations and find the intersection point.

You will see that graph intersect at (4,6) which gives x=4, y=6