Let $A=\{1,2,3, \ldots, 20\}$. Let $R_1$ and $R_2$ two relation on $A$ such that $R_1=\{(a, b): b$ is divisible by $a\}$ $R_2=\{(a, b): a$ is an integral multiple of $b\}$. Then, number of elements in $R_1-R_2$ is equal to _____________.

Question

Let $A=\{1,2,3, \ldots, 20\}$. Let $R_1$ and $R_2$ two relation on $A$ such that

$R_1=\{(a, b): b$ is divisible by $a\}$

$R_2=\{(a, b): a$ is an integral multiple of $b\}$.

Then, number of elements in $R_1-R_2$ is equal to _____________.

Correct Answer

Solution

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