harga 1 buku dan 2 pensil adalah 6.500 sedangkan harga 2 buku dan 1 pensil adalah 8.000. Berapa rupiah harga 3 buku dan 2 pensil?

<p>Jawaban yang tepat adalah Rp. 12.833,33</p><p>&nbsp;</p><p>Pembahasan :</p><p>Misalkan buku = x dan pensil = y</p><p>x + 2y = 6.500 &nbsp;--&gt; x = 6.500 - 2y &nbsp; &nbsp; &nbsp;(1)</p><p>2x + y = 8.000 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (2)</p><p>&nbsp;</p><p>Substitusikan persamaan (1) ke persamaan (2)</p><p>2x + y = 8.000 &nbsp; &nbsp;&nbsp;</p><p>2(6,500 - 2y) + y = 8.000 &nbsp; &nbsp;&nbsp;</p><p>13.000 - 4y + y = 8.000</p><p>13.000 - 3y = 8.000</p><p>3y = 13.000 - 8.000</p><p>3y = 5.000</p><p>y = 5.000/3</p><p>y = 1.666,67</p><p>Harga 1 pensil = Rp. 1.666,67</p><p>&nbsp;</p><p>Substitusikan y = 5000/3 ke persamaan (1)</p><p>x = 6.500 - 2y&nbsp;</p><p>x = 6.500 - 2(5000/3)</p><p>&nbsp; &nbsp; = 6.500 - 10.000/3</p><p>&nbsp; &nbsp; = 19.500/3 - 10.000/3</p><p>&nbsp; &nbsp; = 9.500/3</p><p>&nbsp; &nbsp; = 3.166,67</p><p>Jadi harga 1 buku adalah Rp. 3.166,67</p><p>&nbsp;</p><p>3x + 2y = 3(9.500/3) + 2(5000/3)</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;= 28.500/3 + 10.000/3</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;= 38.500/3</p><p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;= 12.833,33</p><p>&nbsp;</p><p>Jadi &nbsp;harga 3 buku dan 2 pensil adalah Rp. 12.833,33</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p>