Block A is 45 km from Block B. Spring and Autumn start moving from Block A to Block B. Spring cycles 15 km/h and Autumn walks 6 km/h. After arriving at B, Spring stays there for 1 hour and comes back. Then he meets Autumn in between. How far is it from their meeting place to B? ___ km

Autumn walks T hrs = T * 6 km /hr

Spring rides 45 km/ 15 km / hr = 3 hr     time for Spring to ride 45 km

3 hr + 1 hr = 4 hr   time before Spring starts back

T * 6 +  (T - 4) * 15 = 45      Autumn starts back at T - 4 hrs

(6 + 15) T - 60 = 45

21 T = 105

T = 5 hrs

Autumn travel 5 * 6 = 30 km

Spring travels 1 * 15 = 15 km

Total distance traveled = 45 km

Meeting  place is 15 km from B

this means that the temperature of both substances will be equal