How much adenyl thymine guanyl cytidyl nucleotides are contained in a DNA fragment if 800 guanyl nucleotides

How much adenyl thymine guanyl cytidyl nucleotides are contained in a DNA fragment if 800 guanyl nucleotides are found in it, making up 20% of the total number of nucleotides in this DNA fragment.

In the DNA molecule, adenyl (A) is complementary to thymine (T), and guanyl (G) is complementary to cytosine (C).
1. To begin with, you can find the amount of all nucleotides in DNA, for this we will make the proportion:
20% -800 nucleotides
100% -X
X = 4000 nucleotides.
2. We already know about complementarity, we will use this property to establish the amount of each type of nucleotide:
A = T, therefore 800 = 800, together there are 1600.
C = G, together there will be 4000-1600 = 2400, therefore C = 1200; G = 1200 nucleotides.
Answer: A = 800; T = 800; C = 1200; G = 1200 nucleotides.