View Compilation Error

207317_0_23863.c: In function `main':
207317_0_23863.c:10: error: `b1' undeclared (first use in this function)
207317_0_23863.c:10: error: (Each undeclared identifier is reported only once
207317_0_23863.c:10: error: for each function it appears in.)
207317_0_23863.c: At top level:
207317_0_23863.c:51: error: syntax error before "return"