MHB Solving equation with 2 variables. (time sensitive)

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The discussion revolves around solving a two-variable algebra word problem involving Ashlee's jewelry sales. The equation modeled is 6a + 12b = 168, where 'a' represents bracelets and 'b' represents necklaces. The user successfully isolates 'b' as b = 14 - 0.5a but struggles to find unique solutions due to the lack of a second equation. It is concluded that while multiple combinations of 'a' and 'b' exist, the problem primarily asks for 'b' in terms of 'a'. The final confirmation is that the user's work is correct, and they are not alone in their confusion.
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i am a 50 year old man, lovingly arguing with my 12 year old niece who has an algebra word problem. we're stumped (I'M stumped) -- and would love to get some help. CAN YOU PLEASE HELP ME SOLVE THIS "2 VARIABLE" PROBLEM ASAP (need it by 6am pacific time on 10/7/14). thanks! PROBLEM: Ashlee makes beaded jewelry. She charges 6dollars for a bracelet and 12dollars for a necklace. She earned $168. Let "a" equal the number of bracelets and "b" equal the number of necklaces.
Problem #1: write an equation to model the situation.
Problem #2: Solve for "b".

re #1, my answer is: 6(a) + 12(b) = 168. (correct?)
re #2, I'm stumped. the way I'm TRYING to solve is to isolate "b" (aka, the number of necklaces she sold) on one side of the equation. I'm going like this:
step 1: 6(a) + 12(b) = 168
step 2: divide all groups by 12, giving me
step 3: .5(a) + b = 14. then
step 4: b = 14 - .5(a)
at this point, i hit a wall.
my niece says it can't be answered. i say, they wouldn't put it in the book if it couldn't be answered. THOUGHTS? THANKS!
 
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Your work is correct...I get:

$$b=\frac{28-a}{2}$$

which is equivalent to your solution.

Now, since we are not given another equation, such as the total number of items Ashlee sold, we cannot get a unique solution, however, we know b must be a whole number, so we then conclude that the only possible solutions are:

$$(a,b)=(0,14),\,(2,13),\,(4,12),\,(6,11),\,(8,10),\,(10,9),\,(12,8),\,(14,7),\,(16,6),\,(18,5),\,(20,4),\,(22,3),\,(24,2),\,(26,1),\,(28,0)$$

But, I suspect they are not asking for the possible solutions, just for $b$ in terms of $a$, which you correctly found.
 
mark. thank you for your stab at this. glad to hear that I'm not the only one coming to that conclusion! much appreciated.
MarkFL said:
Your work is correct...I get:

$$b=\frac{28-a}{2}$$

which is equivalent to your solution.

Now, since we are not given another equation, such as the total number of items Ashlee sold, we cannot get a unique solution, however, we know b must be a whole number, so we then conclude that the only possible solutions are:

$$(a,b)=(0,14),\,(2,13),\,(4,12),\,(6,11),\,(8,10),\,(10,9),\,(12,8),\,(14,7),\,(16,6),\,(18,5),\,(20,4),\,(22,3),\,(24,2),\,(26,1),\,(28,0)$$

But, I suspect they are not asking for the possible solutions, just for $b$ in terms of $a$, which you correctly found.
 
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