It is known that S2 + S1 = 1.2m, S1: S2 = 3:7, and the total length of the inclined plane is 1.2m?

It is known that S2 + S1 = 1.2m, S1: S2 = 3:7, and the total length of the inclined plane is 1.2m?

I thought about it for a while, but I didn't find a shortcut, so I had to say this not too simple method:
s2+s1=1.2m
s1:s2=3:7
Simulink S1 = 0.36M S2 = 0.84M
Calculate a = 0.08 from S1 = 1 / 2 * a * 9
The total length of inclined plane L
L=1/2 a t^2
L-s2=1/2 a (t-3)^2
T = 5S and L = 1m can be obtained simultaneously