$${\textbf{Step -1: Converting half an hour into minute.}}$$
$${\text{As we know that, }}$$
$${\text{1 hour }} \to $$ $${\text{60 min}}{\text{.}}$$
$$\therefore \dfrac{1}{2}$$ $${\text{hour}} \to $$ $$\dfrac{{60}}{2} = 30\min $$
$${\text{It implies that Reema can type 540 words in 30min}}$$
$${\text{i}}{\text{.e}}{\text{.}}$$ $$30\min \to 540$$ $${\text{words}}$$
$$\therefore 1\min \to $$ $$\dfrac{{540}}{{30}} = 18$$ $${\text{words}}$$
$${\textbf{Step -2: Calculating number of Words typed in 6minutes}}$$
$$\because 1\min \to 18{\text{words}}$$
$$\therefore 6\min \to 18 \times 6 = 108{\text{words}}$$
$${\textbf{ Hence, Reema can type 108 words in 6 minutes.}}$$