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Answer:
D) a + 2c = 10.5
Step-by-step explanation:
The given relations can be written using the equations ...
a +b +c = 10
b = 2a
b = c +0.5
Substituting the second equation into the first, we get ...
a +2a +c = 10
3a +c = 10 . . . . . . . . simplified
The equations in bold above are ones that apply in this situation.
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If we substitute the third equation into the first, we get ...
a + (c +0.5) + c = 10
a +2c = 9.5 . . . . . . . . . . subtract 0.5 from both sides, simplify
Note that this does not match the equation of answer choice D, which is NOT true for this situation.