Concept 1Sum of angles on a straight line is 180∘Angle SRP+ Angle PRS=180Angle SRP+2x−10=180Angle SRP=180−2x+10Angle SRP =180+10−2xAngle SRP=190−2x Concept 2The interior angles of equilateral triangle are the same.Angle SRP= Angle RPQ= Angle PQR=190−2x Concept 3The sum of interior angles of a triangle gives 180∘Angle SRP+ Angle RPQ+ Angle PQR=180(190−2x)+(190−2x)+(190−2x)=1803x(190−2x)=180Divide both sides by 3190−2x=3180190−2x=60−2x=60−190−2x=−130Divide both sides by -2−2−2x=−2−130x=65
