Which two colours make blue?

none : ( Blue IS a PRIME Color,just like yellow & red.

Since blue is a primary color, it cannot be made using other colors such as red and yellow.
There are no colors that make blue. Blue is a primary color and stands alone. It is one of the three basic colors from which all oter colors are mixed.
Green yellow

is the last answer, the real answer is nothing. blue is a primary colour which means that you cant make it. and green and yellow together just makes a lighter shade of green because ble and yellow makes green, not the other way around.
Blue is a primary color. Primary colors (red, yellow, blue) are never made from other colors.