Getting shape error in the layer

I am doing house price prediction challange in neural networks and getting layer shape error but not able to get the reason.
here is the link to my notebook:-
https://colab.research.google.com/drive/1Co2GFOgDKG6C_1AntoGv0fvtYKDVYlTF

the error is at the end of notebook
please have a look.