Discussion
A certain brand of computer can be bought with or without a hard drive. The computer with the hard drive costs 2,900 dollars. The computer without the hard drive costs 1,950 dollars more than the hard drive alone. What is the cost of the hard drive?
*This question is included in Nova Math - Problem Set Z: Miscellaneous Problems, question #1
| (A) | 400 |
| (B) | ... |
| (C) | ... |
| (D) | ... |
| (E) | ... |
| (F) | ... |
The solution is
Posted: 09/19/2012 10:57
I didn't understand how we solved for H when we combined the equations :(
Posted: 09/19/2012 17:44
Salma,
Let's set up the problem this way. That's 90% of the solving, and I hope it helps you understand more clearly.
Cost of hard drive = HD
Computer with hard drive = CHD
Computer without hard drive = CXD
CHD = CXD + HD; computer can be bought with or without hard drive
CXD = 1950 + HD; computer without the hard drive costs 1,950 dollars more than the hard drive alone
CHD = 2900; The computer with the hard drive costs 2,900
2900 = CXD + HD
1950 = CXD - HD
Two equations, two unknowns. Solve for HD by subtracting 2nd from the first equation:
950 = 2HD
HD = 475
Let's set up the problem this way. That's 90% of the solving, and I hope it helps you understand more clearly.
Cost of hard drive = HD
Computer with hard drive = CHD
Computer without hard drive = CXD
CHD = CXD + HD; computer can be bought with or without hard drive
CXD = 1950 + HD; computer without the hard drive costs 1,950 dollars more than the hard drive alone
CHD = 2900; The computer with the hard drive costs 2,900
2900 = CXD + HD
1950 = CXD - HD
Two equations, two unknowns. Solve for HD by subtracting 2nd from the first equation:
950 = 2HD
HD = 475
Posted: 10/30/2015 10:54
Thanks