At the "Murah" bookstore, Adi buys 4 books, 2 pens and 3 pencils for Rp26,000. Bima buys 3 books, 3 pens and 1 pencil for Rp21,500. Citra buys 3 books and 1 pencil for Rp12,500.
If Dina buys 2 pens and 2 pencils, then she must pay ....
Explanation
Let the price of 1 book =x, 1 pen =y, 1 pencil =z
We obtain the following equations
Adi: 4x+2y+3z=26,000...(i)
Bima: 3x+3y+z=21,500...(ii)
Citra: 3x+z=12,500...(iii)
From equation (iii), we get
z=12,500−3x
Substitute z into equation (ii)
3x+3y+(12,500−3x)=21,500
3y+12,500=21,500
3y=9,000
y=3,000
Substitute z and y into equation (i)
4x+2(3,000)+3(12,500−3x)=26,000
4x+6,000+37,500−9x=26,000
−5x+43,500=26,000
−5x=−17,500
x=3,500
From x=3,500, we can find z
z=12,500−3(3,500)
z=12,500−10,500=2,000
Dina buys 2 pens and 2 pencils, so the amount to be paid is
