View Compilation Error

229677_0_22018.c: In function `main':
229677_0_22018.c:14: error: `x' undeclared (first use in this function)
229677_0_22018.c:14: error: (Each undeclared identifier is reported only once
229677_0_22018.c:14: error: for each function it appears in.)
229677_0_22018.c:18: error: incompatible types in assignment
229677_0_22018.c:22: error: `sum' undeclared (first use in this function)