Explanation:
taking the rule of angles which state that angles on a straight line add up to 180°
then we take the solution adding the expression then equate to 180°
;5x+4+x-2+3x+7=180
like terms together
5x+x+3x+4+-2+7=180
=9x+9=180
9x=180-9
9x=171
getting the value of x we divide by nine both sides
x=171/9
x=19°