Since bit pattern-011110
Whenever sender data link layer encounters three consecutive ones in the data stream, it automatically stuffs a 0 bit into the outgoing stream.
so msg now -10111001110101110111010
4 zero bits stuffed by transmitter while transmitting given frame.
When the receiver sees three consecutive incoming ones followed by a 0 bit, it automatically destuffs the 0 bit .
So Now Msg- 1011101111011111110