2.4

#include <stdio.h>
struct rectangle{
    double a;
    double h;};
struct x_rectangle{
    struct rectangle rect;
    double rect_pole;};

void oblicz_pole( struct x_rectangle *prostokat)
{
    prostokat->rect_pole=prostokat->rect.a*prostokat->rect.h ;
}

int main(void)
{
    struct x_rectangle prostokat;
    scanf("%lf %lf", &prostokat.rect.a,&prostokat.rect.h );
    oblicz_pole(&prostokat);
    printf("[a = %.2lf]*[h = %.2lf] = %.2lf" , prostokat.rect.a, prostokat.rect.h , prostokat.rect_pole);
    return 0;
}