View Compilation Error

2_14855_1387496_31441.c: In function `mul':
2_14855_1387496_31441.c:13: error: `t' undeclared (first use in this function)
2_14855_1387496_31441.c:13: error: (Each undeclared identifier is reported only once
2_14855_1387496_31441.c:13: error: for each function it appears in.)