Answer:
Cytosine = 30%. Guanine = 30%. Adenine = 20%. Thymine = 20%.
Step-by-step explanation:
Since Cytosine always binds with Guanine, they will have equal percentages of the DNA composition. Since Cytosine and Guanine together make up 60% of the cell's DNA, Adenine and Thymine together make 40% (each with 20%) of the cell's DNA to make up the whole cell's DNA (100%).
Hope this helps!