D=rt when biker A catches biker B, the time they've been riding is the same, so t=t, or d/r=d/r the rates are 6.4 and 4.7, so d/6.4=d/4.7 biker B is 34m ahead, so (d+34)/6.4=d/4.7 multiply both sides by 6.4*4.7: 4.7(d+34)=6.4d 4.7d+=6.4d+159.8 1.7d=159.8 d=94 meters
Another way to think of it is that biker A gains 1.7 meters on B every second (6.4-4.7=1.5), so the time it'll take for him to gain 34 meters is 34/1.7=20 seconds. In that time, biker B travels 4.7*20=94 meters
