If a segment of dna is made up of 40 thymine how much guanine is present

According to Chargaff's rule, [A] + [G] = [C] + [T]

[A]+[G]+[C]+[T] = 100 %

Adenine [A] is paired with Thymine [T], A=T

Cytosine [C} is paired to Guanine [G], G = C

Here,[T] 40 % therefore, % of [A] is also 40%,

Therefore; [G]+[C] = 100% - 80% = 20%

Hence; [G] = 10% and [C] = 10%

Therefore, the percentage of guanine present is 10%