C# Rounding Whole Numbers

I have a question regarding c# and rounding.  Given the following equations c# seems to round them differently based on if a decimal is dictated in the whole number.  Is there any way to tell C# to output 7.5 regardless of the format of the code?

I am in the process of converting some legacy code and I don’t have the option of ensuring the static values are formatted with “.00”.

double test = 3000.00 / 400.00;
test = 7.5;

double test2 = 3000 / 400;
test2 = 7;