Answer: 6a
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Explanation:
Solve the first equation for b
a/b = 6/7
7a = 6b ... cross multiply
6b = 7a
b = 7a/6 ... divided both sides by 6
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Solve the second equation for c
a/c = 2/5
5a = 2c
2c = 5a
c = 5a/2
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We found that
both are in terms of a
So,
3b+c = 3(7a/6) + 5a/2
3b+c = 21a/6 + 5a/2
3b+c = 7a/2 + 5a/2
3b+c = (7a+5a)/2
3b+c = 12a/2
3b+c = 6a
