Let us assume three numbers are \(x\),\(y\) and \(z\)

Now according to the problem

\(x+y=12\).....................(1)

\(y+z=17\)....................(2)

\(z+x=19\)......................(3).

Can you find out the values of \(x\),\(y\) and \(z\)................?

can you finish the problem........

Adding three equations we get \(2(x=y+z)=48\)

\(\Rightarrow x+y+z=24\).............(3)

Now subtract (3) from (1),we will get \(z=12\) and similarly if we subtract (2) and (3) from (1) we will get \(x=7\) and \(y=5\)

can you finish the problem........

Therefore,the numbers are \(12\), \(7\), and \(5\) and middle number is \(7\)