Question

If a DNA strand has 30 guanines how much thymine does it have?

Answer 1

The genetic information of a cell is stored in molecules of deoxyribonucleic acid (DNA).
DNA is a polymer of nucleotides . A DNA molecule consists of three parts—a nitrogen base, a five-carbon sugar called deoxyribose, and a phosphate group.

There are four DNA nucleotides, each with one of the four nitrogen bases (adenine, thymine, cytosine, and guanine). The first letter of each of these four bases is often used to symbolize the respective nucleotide (A for adenine nucleotide, for example).

DNA forms a two-stranded spiral, or double helix. Note that adenine always bonds with thymine and cytosine always bonds with guanine.

You have 30 G and therefore 30 C. But the rest of your answer is unknown without knowing the number of adenine.