Answer:
90 Thymine bases
Step-by-step explanation:
Chargaff's rules states that in the DNA of any organism, the amount of purine and pyrimidine bases must be in a 1:1 ratio. This means that the amount of Adenine and Guanine bases (purines) should be equal with their complementary pairs of Thymine and Cytosine bases respectively (pyrimidines). (A = T) + (G = C) = 100
Hence, according to this question, if there are 60 cytosine bases, this means that there will be 60 Guanine bases. 60 C + 60 G = 120 pyrimidines
300 total bases - 120 pyrimidine bases = 180 purine bases.
180/2 = 90 equal bases of Adenine and Thymine. Hence, Thymine bases will be 90.