They travelled 3 and 5/6 miles, then drove 2 and 2/6 more the next day. To find the total, you must add them up. So...

They travelled for 6 and 1/6 hours, or 6 hours and 10 minutes.
7x+10=1/3×(12x-3)+14x
7x+10=1/3×3(4x-1)+14x
7x+10=(4x-1)+14x
7x+10=4x-1+14x
7x+10=18x-1
7x-18x=-1-10
-11x=-11
x=1
What’s the equation? i don’t see it?
I think it wants you to multiply the numbers.
329×2=658
658×4=2632
Final Answer=2632
They won't arrive exactly when the race starts, but they will arrive before the race starts because, assuming they leave exactly three hours before the race, they can drive a total of 150 miles in three hours (3h*50mi/h). Because they only need to drive 120 miles, they will make it to the race before it starts.