a/3=b/4=a+b/3+4=14/7=2

a/3=2=>a=6;b/4=2=>b=8

We have: \(\dfrac{a}{3}=\dfrac{b}{4}=\dfrac{a+b}{3+4}=\dfrac{14}{7}=2\)

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

=> \(\dfrac{b}{4}=2\) <=> \(b=4\cdot2=8\)