Equilib. eqns

$$FX$=0->$PAB$=4($kN$)($T$)($for cut between A&B$)$

$$FX$=0->$PBC$=(4-$Q$)($kN$)($T$)($for cut between B&C$)$

Deflection of point A

Since C is fixed, deflection of point A $($A$)=$ Increase in length of AC $($AC$)()$

The increase in length of AB is given as $$AB$=$

x$10-2($mm$)$