How many guanine bases a length of DNA will have if it has 26 cytosine bases?

In a double-stranded DNA molecule, the bases pair specifically: adenine pairs with thymine, and guanine pairs with cytosine. This means that for every cytosine base, there is a corresponding guanine base. Therefore, if there are 26 cytosine bases in the DNA, there will also be 26 guanine bases.