Tension Between Three Masses

This problem, i solved for a) by F=ma ..rearranging the equation to a=f/m used the T3/sum of the masses and got a=1.19706m/s2 ...now i got stuck solving for b and c...i feel like i need to know one of the other two tensions to be able to solve this problem because there are forces acting in both directions and i only have the sum of the tension....

In Fig. 5-49, three connected blocks are pulled to the right on a horizontal frictionless table by a force of magnitude *T*3 = 97.8 N. If *m*1 = 14.8 kg, *m*2 = 28.3 kg, and *m*3 = 38.6 kg, calculate (a) the magnitude of the system's acceleration, (b) the tension *T*1, and (c) the tension *T*2.