The GCD of given numbers is 43.
Step 1 : Find prime factorization of each number.
$$\begin{aligned}1505 =& 5\cdot7\cdot43\\[8pt]43 =& 43\\[8pt]\end{aligned}$$(view steps on how to factor 1505 and 43. )
Step 2 : Put a box around factors that are common for all numbers:
$$\begin{aligned}1505 =& 5\cdot7\cdot\color{blue}{\boxed{43}}\\[8pt]43 =& \color{blue}{\boxed{43}}\\[8pt]\end{aligned}$$Step 3 : Multiply the boxed numbers together:
$$ GCD = 43 $$This solution can be visualized using a Venn diagram.
The GCD equals the product of the numbers at the intersection.