What is the statment in c# for this ?! (Mathematical Problem)

Question

I know my quiestion is silly but I'm not good in Math:

I'm writing a program:

I want to count the consumption of water and electricity and phone calls. I know how i want it but i dont know how to translate it to C# statments

1- I created the method decimal getElect(Unit kw)

I want the consumption to be counted as the following:-

-----KW-------------------------Price---

The first 100 kw-------------5---------

The second 100 kw-------10--------

The third 100 kw-----------20--------

More than three------------50--------

---

I will explaine more, for example if the total kw=250 the way to count them is

the cost of the first 100 = 5*100

the cost of the second 100=10*100

the cost of 50 =50*20

total cost will be = 500+1000+1000=2500

==================================================================================

2- I created the method decimal getWater(unit m3)

I want the consumption to be counted as the following:-

-----M3-------------------------Price---

0 ....100---------------------5---------

100 ....200-----------------10--------

200....300------------------20--------

More than that---------------50--------

---

I will explaine more, for example if M3=150

the cost =150*10=1500

=====================================================================================

Answer 1

These should work for you...

public decimal getElect(decimal kw)
{
//a stores unit count @ 5
//b stores unit count @ 10
//c stores unit count @ 20
//d stores unit count @ 50


    decimal a = 0, b = 0, c = 0, d = 0;

    a = (kw > 100) ? 100 : kw ;
    b = (kw > 200) ? 100 : ((kw - 100) > 0 ? kw - 100 : 0);
    c = (kw > 300) ? 100 : ((kw - 200) > 0 ? kw - 200 : 0);
    d = ((kw - 300) > 0) ? kw - 300 : 0;

    return (a * 5) + (b * 10) + (c * 20) + (d * 50);
}

public decimal getWater(decimal m3)
{
    int multip = 5;
    if (m3 > 100) multip = 10;
    if (m3 > 200) multip = 20;
    if (m3 > 300) multip = 50;

    return m3 * multip;
}

Answer 2

// returns zero if x is negative, returns x if x is positive
int z(int x)
{
     return (x > 0) ? x : 0;
}

// returns zero if x is negative, returns 1 if x is positive
int s(int x)
{
     return (x > 0) ? 1 : 0;
}

// we'll pay at least 5 for each kw plus at least 5 for each kw above 100 etc.
int getElect(int kw)
{
    return 5 * kw + 5 * z(kw - 100) + 10 * z(kw - 200) + 30 * z(kw - 300);
}

// we'll pay at least 5 for each m3 plus at least 5 for each m3 if m3 is above 100 etc.
int getWater(int m3)
{
    return 5 * m3 + 5 * m3 * s(m3 - 100) + 10 * m3 * s(m3 - 200) + 30 * m3 * s(m3 - 300);
}