Evaluate 7 - (-19) - 18 + (-19) + 18

Aconvex octagon has interior angles that measures 73 degrees, 172 degrees, 132 degrees, 59 degrees, 154 degrees, 163 degrees, x degrees, 2x degrees find the value of the missing angles

Arley is building a model of a city map. in one part of the city, three roads form a right triangle, which harley draws as triangle abc, with the following measures: m∠b=90° and m∠a=30°. in his scale model, the hypotenuse of triangle abc, ac¯¯¯¯¯¯¯¯, has a length of 817−−√ cm. what is the value of a (the length of bc¯¯¯¯¯¯¯¯)?

Lena reflected this figure across the x-axis. she writes the vertices of the image as a'(−2, 8), b'(−5, 6), c'(−8, 8), d'(−4, 2).