Question 22
Let $a,$ $b,$ $c,$ and $d$ be positive integers such that $$
\gcd(a, b)=24,
$$ $$
\gcd(b, c)=36,
$$ $$
\gcd(c, d)=54,
$$ and $$
70 < \gcd(d, a) < 100.
$$ Which of the following must be a divisor of $a?$
\gcd(a, b)=24,
$$ $$
\gcd(b, c)=36,
$$ $$
\gcd(c, d)=54,
$$ and $$
70 < \gcd(d, a) < 100.
$$ Which of the following must be a divisor of $a?$