Answer:
x = 8
Step-by-step explanation:
See the diagram first which is attached.
We see from the diagram that Δ RST is an equilateral triangle having equal length of its sides i.e. RS = ST = TR
Hence, the angles of the triangle will also be the same and equal to 60°.
Now, ∠ S = 60 = 7x +4 {Given}
⇒ 7x = 56
⇒ x = 8 (Answer)