10x+x+3=4(x+x+3)

Solution: x = 3

x+3=3+3=6

This two-digit number is 36.

2. After setting X hours, car B will catch up with car A. ..

72x= 48×(x+25/60)

Solution: x = 5/6

After 5/6 hours, the B car caught up with the A car. ..