diff --git a/1-15.c b/1-15.c
new file mode 100644
index 0000000..0463d49
--- /dev/null
+++ b/1-15.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+double fahr_to_celsius(int fahr){
+  return (5.0/9.0)*(fahr-32);
+}
+int main(){
+  int fahr;
+  for (fahr=300; fahr>=0; fahr-=20){
+    printf("%3d %6.1f\n", fahr, fahr_to_celsius(fahr));
+  }
+}