Answer
300 ft
Explanation :
Since 1 yard = 3 feet, we can multiply 100 yd by $$\dfrac{3 ft}{1 yd} $$ We are essentially multiplying by 1, but doing so allows us to cancel out the yd unit so that we are left with only ft.
$$ \dfrac{100 yd}{1}.\dfrac{3 ft}{1 yd} = 300 ft $$