SOLUTION: It's been a long time since I've done Algebra and I don't know how to help my daughter with this one.... A banana contains 3 more milligrams (mg) of calcium than an apple and 40

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Question 103236: It's been a long time since I've done Algebra and I don't know how to help my daughter with this one....
A banana contains 3 more milligrams (mg) of calcium than an apple and 40 mg of calcium less than an orange. How much calcium is there in an orange if it contains the same amount as 5 apples and a banana.
I'd like to see how this is written out in equation form....not just get the answer.
Found 3 solutions by stanbon, scott8148, edjones:
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website!
A banana contains 3 more milligrams (mg) of calcium than an apple and 40 mg of calcium less than an orange. How much calcium is there in an orange if it contains the same amount as 5 apples and a banana.
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banana = "b" ; apple = "a" ; orange = "r"
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EQUATIONS:
b = a+3
b = r-40
5a+ b =r
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Rearrange:
1a - 1b + 0r = -3
0a + 1b - 1r = -40
5a + 1b - 1r = 0
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Using a TI calculator I get:
a = 8 ; b = 11 ; r = 51
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Cheers,
Stan H.

Answer by scott8148(6628)   (Show Source):
You can put this solution on YOUR website!
B=A+3 ... B=�-40 ... A=�-43
�=5A+B ... substituting for A and B gives �=5(�-43)+(�-40)

�=5�-215+�-40 ... �=6�-255 ... 255=5� ... 51=�

Answer by edjones(8007)   (Show Source):
You can put this solution on YOUR website!
a=mg of Ca in an apple, b=mg of Ca in a bannana, g=mg of Ca in an orange
b=a+3...a=b-3
g=b+40
g=5a+b...g=5(b-3)+b...g=5b-15+b...g=6b-15...g-6b=-15
.
g=b+40
C) g-6b=-15
.
replace b+40 for g in equation C)
b+40-6b=-15
-5b+40=-15
-5b=-55 subtract 40 from each side.
b=11 mg divide each by -5.
a=8 mg
g=51 mg
.
Ed