added substraction

explelibx-common/exple-substract.cpp

+//
+// Created by Andrey Debolskiy on 16.04.2022.
+//
+#include "exple-substract.h"
+
+int exple::substract(int a, int b)
+{
+    return (a - b) ;
+}

explelibx-common/exple-substract.h

+//
+// Created by Andrey Debolskiy on 16.04.2022.
+//
+
+#ifndef EXPLE_CMAKE_BUILD_EXPLE_SUBSTRACT_H
+#define EXPLE_CMAKE_BUILD_EXPLE_SUBSTRACT_H
+
+namespace exple
+{
+    int substract( int a, int b);
+}
+
+#endif //EXPLE_CMAKE_BUILD_EXPLE_SUBSTRACT_H

[Vladimir Onoprienko]

A typo: substract -> subtract