If the equation x2 ax 12 0 x2 bx 15 0 and x2 a b x 36 0 have a common positive root then the ordered...........

If the equation x² + ax +12=0, x² +bx+15=0 and x² + (a+b)x+36=0 have a common positive root,then the ordered pair (a,b) is

(-6, -7)

(-7, -9)