Answer:
y+30
Step-by-step explanation:
the sum of the numbers is 15y
the new sum after increase each number by 30 is 15y+450
the new mean 15y+450/15
= y+30
The second choice is correct. Given that angle 2 and angle 6 are congruent, the largest in each of the corresponding triangles are vertical angles meaning that two known angles are known in each triangle (and they are equal) which means that the last "unknown" (angles 3 and 7) are congruent. The lines DC and AB correspond with these defined, congruent triangles meaning they are parallel.
