X+Y=0.75

3X+5Y=3.25

Y=0.75-X

3X+5(0.75-X)=3.25

-2X=-0.5

X=0.25

Y=0.5

Let the total length be x, and Xiaoming runs y meters per second.

25*4=X

25Y+ 10=X

X= 100

Y=3.6