输入后，我的程序似乎跳过了第一个IF语句，直接转到ELSE

我的代码有问题。它编译时没有错误，但在从用户那里获得输入后，即使有正确的值，它似乎也会跳过第一个条件语句，直接转到ELSE，从而导致程序终止。我似乎找不出这种行为的原因。

我认为这可能是条件语句构造方式的问题：if( ((S <= 25 && S <= 75) % 5 == 0) && (U < 0.2 && U < 0.7) ){

我需要检查输入的值是否是25 <= S <= 75，是否可以被5整除，以及另一个值是否为0.2 < U < 0.7

课程分配

//#include "stdafx.h" // Header File used VS.
#include <iostream>
//#include <iomanip> // Used to format the output.
#include <cstdlib> // Used for system().
#include <math.h> // Used for sqrt().
using namespace std;// ?

int main (){
int S; // Gram/Litre
double U; // Specific Max. Growth Rate. Per Hour.
double D; // Maximum Dilution Rate.
const int K = rand() % 7 + 2; // Saturation Constant - Randomly Gegerated Number Between 2 & 7. In Hour/Litre.
cout << "Enter value between 25 and 75, divisible by 5, for S in Gram/Litre: ";
cin >> S;
cout << "Enter value bigger than 0.2, but less than 0.7, for U per Hour: ";
cin >> U;
if( ((S <= 25 && S <= 75) % 5 == 0) && (U < 0.2 && U < 0.7) ){ // Check Condition ***May Need Adjustments***
D = U * ( 1 - sqrt ( K / ( K + S) ) ); // Might have to adjust values to fit data type double. Add .00
cout.precision(3); // Prints 3 values after decimal point.
cout << "Maximum dilution rate is: " << D << endl;
if( D < 0.35 && D < 0.45 ){
cout << "Kinetic parameters are acceptable." << endl;
}
else{
cout << "Kinetic  parameters are not acceptable." << endl;
}
}
else{
cout << "Invalid Input. Program will now terminate." << endl;
}
system("PAUSE"); // Pauses the program before termination.
return 0;
}