test.c

#include <stdio.h>

float float_1( float a, float b ) {
    return a + b;
}

float float2( float a, float b ) {
    return a + b;
}

float float3( float a, float b, float c ) {
    return a + b + c;
}

int main() {
    float var = float_1( float2(5.5, 10.0), float3(11.0, 2.5, 3.3) );
    printf("%f\n", var);
    return 0;
}