Apply the same ratio. We have:

\(\dfrac{a}{6}=\dfrac{b}{3}=\dfrac{c}{12}=\dfrac{a-b+c}{6-3+12}=30\)

<=> \(\dfrac{a-b+c}{15}=30\)

But 30 : 15 = 2

=>\(a=6.2=12\)

=> b = 3 . 2 = 6

=> c = 12 . 2 = 24

We have:

a/6=b/3=c/12=a-b+c/6-3+12=30/15=2

a/6=2=>a=12

b/3=2=>b=6

c/12=2=>c=24

We have: \(\dfrac{a}{6}=\dfrac{b}{3}=\dfrac{c}{12}=\dfrac{a-b+c}{6-3+12}=\dfrac{30}{15}=2\)

=> \(\dfrac{a}{6}=2\) <=> \(a=6\cdot2=12\)

=> \(\dfrac{b}{3}=2\) <=> \(b=3\cdot2=6\)

=> \(\dfrac{c}{12}=2\) <=> \(c=12\cdot2=24\)