ComboBox and TextBox with Same Functions

Good day To All, i was wondering is there any possibility

Winform Items

A.) 1~5 ComboBox

B.) 1~5 Textbox for Time (i'll identify them for example as txtTime1 ~ txtTime5)

C.) 1~5 Textbox for Amount (i'll identify them for example as txtAmount1 ~ txtAmount5)

Items 1 ~ 5 (ComboBox 1-5 , txtTime 1-5, txtAmount 1-5) will do the same Functions.

A.)

if (combobox1.SelectedValue.ToString() == "Regular")
    {
        x = 1.25;
    }
else if (combobox1.SelectedValue.ToString() == "Double")
    {
        x = 2;
    }
 // Same Codes for ComboBox 2~5

B.)Textbox "txtTime(s)" will hold a TextChange Event fetching values of our said comboBoxes

if (txtTime.Text.Lenght > 0)
    {
    // Item Letter "C"
    // value of "x" is equal to the above item
    txtAmount.Text = (double.Parse(txtTime.Text) * x).ToString();
    }

i just need a quick idea on how will i make this work

Thank You in Advance