Which vehicle will proceed through the intersection first?

Explanation

There are no signs, so this is an intersection of roads of equal rank, where you give way to vehicles approaching from the right. Nobody approaches the green car from its right and the oncoming yellow car is turning left, so the green car has no one to give way to. The green car is on the right of the blue and red cars, and they are on the yellow car's right, so the green car goes first (Rules, points 98 and 99).