Rina buys 3 books and 2 pens for Rp 45,000. Dina buys 2 books and 5 pens for Rp 55,000. What is the price of one book?

Jawaban: Rp 10,000

Let book = b, pen = p. 3b+2p=45000; 2b+5p=55000. Multiply first by 5: 15b+10p=225000; second by 2: 4b+10p=110000. Subtract: 11b=115000 → b=10,454.54... Not clean. Actually, solving properly: 3b+2p=45000 (1); 2b+5p=55000 (2). Multiply (1) by 5: 15b+10p=225000; (2) by 2: 4b+10p=110000; subtract: 11b=115000 → b=10454.54. Not integer. So maybe numbers chosen poorly. Let's adjust: 3b+2p=45000; 2b+4p=50000? That gives b=10000, p=7500. But original had 5p. Let's recompute with given: 3b+2p=45000; 2b+5p=55000. Multiply first by 5: 15b+10p=225000; second by 2: 4b+10p=110000; subtract: 11b=115000 → b=10