Suppose you fire a rifle bullet (1685 m/s) in a shooting gallery and hear the gong on the target ring 0.741 s

please help!

is the question how far away is the target?

it takes the bullet a certain amount of time to reach the gong, and it takes sound some time to return

then we have that 0.741 s = time for bullet to reach gong + time for sound to return

if D is the distance, then time for bullet to reach gong is D/1685
and the time for sound to return is D/330 using 330m/s as the speed of sound

therefore we have

0.741 = D/1685 +D/330

or D=204m