One strand of a double-stranded DNA has the composition $23%$ A, $29%$ T, $27%$ G and $21%$ C (of the bases in that strand). What is the percentage of adenine among all the bases of the duplex (both strands)? (Give a number to the nearest integer.)

Numerical answer type, tolerance 0.5.

Answer: 26

A in the duplex equals (A in strand 1 + A in strand 2)/2. A in strand 2 equals T in strand 1, which is 29%. So %A =

(23 + 29) /2 = 26%