Calculating Masses from Disc Explosion Velocities

[puregoodboi]

Two frictionless discs on air table, initially at rest, are driven apart by an explosion with velocities of 9.0m/s and 5.0m/s what is ratio of masses?
how do i get masses if i don't know Momentum ? +__+

 

[ColdRifle]

m1u1=m2u2 Since we want the ratio of m1 and m2 we make m2=m1*k(a constant)
m1(9m/s)=m1*k*5m/s
k=9/5 So the ratio of the two masses is that the 1st has the 5/9 of the seconds mass

 

[puregoodboi]

m1u1=m2u2 Since we want the ratio of m1 and m2 we make m2=m1*k(a constant)
m1(9m/s)=m1*k*5m/s
k=9/5 So the ratio of the two masses is that the 1st has the 5/9 of the seconds mass

the answer key says its 0.36 .. why's that?

 

[ColdRifle]

I have no idea...maybe they made a mistake or I did one...lol