Solve and fill in the blanks

Explanation

All the blocks more with common acceleration a under the force F = 60 N.
`F = (m_1 + m_2 + m_3) a`
` a= (F)/(m_1 + m_2 +m_3) = 1 m//s^2`

`F= T_2 = m_3 a `
solving we get ` T_1 = 30 N`