SOLUTION: Elva invested $2100 in the stock market. she purchased shares in world oil at $7.50 shares, and zinco Mines at $3.25 / share. if the total number of shares was 450, how many for e

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: Elva invested $2100 in the stock market. she purchased shares in world oil at $7.50 shares, and zinco Mines at $3.25 / share. if the total number of shares was 450, how many for e      Log On


   



Question 1128687: Elva invested $2100 in the stock market. she purchased shares in world oil at $7.50 shares, and zinco Mines at $3.25 / share. if the total number of shares was 450, how many for each stock did she buy ?
Found 2 solutions by josmiceli, MathTherapy:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = number of share of World Oil
Let +b+ = number of shares of Zinco Mines
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(1) +a+%2B+b+=+450+
(2) +7.5a+%2B+3.25b+=+2100+
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(2) +750a+%2B+325b+=+210000+
Multiply both sides of (1) by +325+ and
subtract (1) from (2)
(1) +-325a+-+325b+=+-146250+
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+425a+=+63750+
+a+=+150+
and
(1) +150+%2B+b+=+450+
(1) +b+=+300+
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150 shares of World Oil
300 shares of Zinco Mines
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check:
(2) +7.5a+%2B+3.25b+=+2100+
(2) +7.5%2A150+%2B+3.25%2A300+=+2100+
(2) +1125+%2B+975+=+2100+
(2) +2100+=+2100+
Ok

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
Elva invested $2100 in the stock market. she purchased shares in world oil at $7.50 shares, and zinco Mines at $3.25 / share. if the total number of shares was 450, how many for each stock did she buy?
Let amount of World Oil shares purchased be W
Then number of Zinco Mines shares purchased = 450 -W
Then we get: 7.5W + 3.25(450 - W) = 2,100
7.5W + 1,462.5 - 3.25W = 2,100
4.25W = 637.5
W, or number of World Oil shares purchased = highlight_green%28matrix%281%2C3%2C+637.5%2F4.25%2C+%22=%22%2C+150%29%29
Number of Zinco Mines shares purchased: highlight_green%28matrix%281%2C3%2C+450+-+150%2C+%22=%22%2C+300%29%29