Answer:
50 degrees
Explanation:
Is that a right angle indicator joining that 40 degrees with the unknown angle? If so, then that makes things simple because you can simply use the rule of complementary angles.
90 = 40 + x, x being the unknown angle.
x = 50
And using the power of vertical angles theorem, we can use that 50 degrees to find that to be the angle measure created by First St. and Main St.