geometry help

y  is supplemental to the 131°  angle

So  y  =   180  - 131  = 49°

And this angle is vertical to the bottom left vertex angle of the top triangle  =  49

Tha angle supplemental to the 142° angle at the bottom is 180 - 142  = 38°

So angle  w   = 180  - 38  - 49  = 93°

And by the exterior angle theorem....w =  the sum of 42°  and the angle vertical to the bottom right vertex angle of the top triangle  

So this angle  =    93 - 42   =  51°

So....t  =  180  - 51  - 49  =  180 - 100   =  80°