What will be the tension `T_(1) and T_(2)` in the given figure ?

Explanation

Accelerating of blocks ,
` A = ("Net accelerating force")/("Total mass ")`
` ((78-6)N)/( (5+4+3)kg)`
` 6 m//s^(2)`
FBD of 5 kg:
` T_(1) - 6 N = 5 a`
` T_(1) = 6+5 xx6 `
` 36 N`
FBD of 3 kg :
` 78 - T_(2) = 3a`
`T_(2) = 78 - 3a`
` 78 - 18`
` 60 N`