AT-OEMO-REG 2015 Problem 1

Determine all triples $(a,b,c)$ of positive integers satisfying the conditions $\gcd(a,20) = b$ $\gcd(b,15) = c$ $\gcd(a,c) = 5$ (Richard Henner)

Dataset text AI-MO AoPS. Quoted with source.

Solutions

No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.