Last week, Dolly bought x kg of grade B coffee powder for $12. If she bought grade A coffee powder instead, she would get 200 g less for $12. This week, the price of coffee powder for both grades increased by $5.00 per kg. If Dolly buys grade A coffee powder instead of grade B coffee powder, she will get 120 g less for $12.
Find how much grade B coffee powder Dolly bought last week.
I am thinking on the lines of quantity for week 2 x unit price for week 2 = 12 will yield a quadratic equation to solve.
But, I am confused with the second half of the problem. Does the 120 g less mean that she will get grade A coffee less that grade A for previous week or less that grade B this week?
Thanks for your help.
Edit: Sorry forgot the question part!
Thanks @earboth for your help.
I forgot the most important part of the question, Sorry! The question is, Find how much grade B coffee powder Dolly bought last week.
I am a little confused about your use of x. The question has the variable x with x Kg of grade B coffee powder. Is this a different variable x? I solved the equation assuming a different x. And got x = 40 kg, so corresponding grade B would be 40.2 Kg. This doesn't fit the answer at the back, which is x = 0.8 Kg. Did i solve it right?
2. From the 1st equation (of post #2) you'll get:
3. Replace the variable x by this term:
4. Solve for a. I've got a = $20 per kg of B-coffee(The negative solution isn't very plausible here!)
5. Then . So Dolly bought 0.8 kg B-coffee and she would have got 0.6 kg A-coffee for the same price.