I need help with a program

[MCsheepy]

I'm learning to code in C with the help of a friend, but a code that I'm trying to write doesn't work
int number (int x) {
int n = 2 * x + 4;
return n;
}
int main () {
int x = 10;
printf("The answer is %d\n", n);
}
What I'm trying to do is for the formula to get solved with the input from int main, but it just tells me that x inst defined. I tried swapping around some of the intigers, but it doesn't work at all.

 

[FResher]

int number (int x) {
return 2 * x + 4;

}
int main () {
int x = 10;
printf("The answer is %d\n", number(10));
printf("The answer is %d\n", number(x));
}

 

[MCsheepy]

int number (int x) {
return 2 * x + 4;

}
int main () {
int x = 10;
printf("The answer is %d\n", number(10));
printf("The answer is %d\n", number(x));
}

Thank you so much!