private void btBack_Click(object sender, EventArgs e)
{
Form4_SatementOfSalary f = Form4_SatementOfSalary.GetInstance;
f.Show();
this.Hide(); //Hide curent window form
}
private void btNext_Click(object sender, EventArgs e)
{
//save data for pdf file
UserInput_InvestmentTaxCredit();
Form4_SatementOfSalary f = Form4_SatementOfSalary.GetInstance;
f.Show(); //showing "Satement Of Salary" form
this.Hide(); //hiding investment tex credit form
}