Having trouble with figuring out monthly income tax using if else statements and #include

#include <iostream>
#include <iomanip>
#include <cmath>

using namespace std;

int main()
{
int a = 175;
int b = 883;
int c = 3050;
int d = 7142;
int e = 14708;
int f = 31771;

double monthlyGross, mt;
cout <<"Enter monthly gross pay amount: ";
cin >> monthlyGross;
if( monthlyGross >= a <= b ); 
cout << "Your monthly tax is" << (0.00 + monthlyGross(0.10)) << endl; 
else if  (monthlyGross >= b && <= c ); 
cout << "Your monthly tax is" << (70.80 + monthlyGross(0.15)) << endl; 
else if  (monthlyGross >= c && <= d ); 
cout << "Your monthly tax is" << (395.85 + monthlyGross(0.25)) << endl; 
else if  (monthlyGross >= d && <= e ); 
cout << "Your monthly tax is" << (1418.85 + monthlyGross(0.28)) << endl; 
else if  (monthlyGross >= e && <= f ); 
cout << "Your monthly tax is" << (3537.33 + monthlyGross(0.33)) << endl;
else 
(monthlyGross >= f ); 
cout << "Your monthly tax is" << (9168.12 + monthlyGross(0.35)) << endl;


return 0;

}

Does anyone think that they can help me with this? I have been working on this for probably an hour XD I know it is probably a simple code for most people on here which is why I am here, was hoping somebody that knows what they are doing could help me.