72
If Rectangle- x,
Star- y,
Triangle- z,
we have
3x+y=67 --------> (1)
x+2y+z=79 --------> (2)
2y+2z=84 --------> (3)
2x+y+z=?
(3) => y+z=42, considering this in (2) --> x+y+42=79 => x+y=37, considering this in (1) --> 2x+37=67 => x=15
Then we find that y=22 and z=20
2x+y+z=72
