Which expression is equivalent to mc012-1.jp g? mc012-2.jp g mc012-3.jp g mc012-4.jp g mc012-5.jp g

Ok so let T=time from when Tim starts
Distance Tim travels= T*90
Distance Dora travels=T*75 + 75  (<as already started)
for him to have caught up His distance must equal hers so:
90T=75T + 75  (now minus 75T)
15T=75  (now divide by 15)
T=5 :)
So five hourse, hope this helped :)