Hey there!
x + 19 + 7x + 9 = 180°
1x + 19 + 7x + 9 = 180°
8x + 28 = 180°
SUBTRACT 28 to BOTH SIDES
8x + 28 - 28 = 180° - 28
SIMPLIFY IT!
8x = 180 - 28
8x = 152
DIVIDE 8 to BOTH SIDES
8x/8 = 152/8
SIMPLIFY IT!
x = 152/8
x = 19
Therefore, your answer should be:
x = 19
Good luck on your assignment & enjoy your day!
~Amphitrite1040:)