Arjun should have divided both sides of the equation by 7 instead of multiplying.
Use the king Henry method
3. ΔPQR ≅ ΔSRT
3. ASA (Angle - Side - Angle) - we have two triangles where we know two angles and the included side are equal
If two sides and the included angle of one triangle are equal to the corresponding sides and angle of another triangle, the triangles are congruent.
4. PR ≅ SR
4. ΔPQR ≅ ΔSRT - the corresponding sides are congruent.
