Let p1 (tensile) and p2 (compressive) be the final stresses in the bolt and tube respectively.
For equilibrium,
(tensile force in 1) - (compressive force in 2) = external tensile force
\(\therefore\) p1A1 - p2A2 = 50000
700p1 - 500p2 = 50000
p1 - 0.714p2 = 71.43 (1)
From compatibility,
(total extension of bolt) + (total compression of tube) = movement of nut
\(\Delta\)1 + \(\Delta\)2 = movement of nut
Solving (1) and (2)
p1 = 138.62 N/mm2 (tensile) and p2 = 94.1 N/mm2 (compressive)