Question 13 pls. Brainliest for the first answer

Prove that the value of the expression 7^8–7^7+7^6 is divisible by 43.

What is the next step in the given proof? choose the most logical approach. a. statement: m 1 + m 2 + 2(m 3) = 180° reason: angle addition b. statement: m 1 + m 3 = m 2 + m 3 reason: transitive property of equality c. statement: m 1 = m 2 reason: subtraction property of equality d. statement: m 1 + m 2 = m 2 + m 3 reason: substitution property of equality e. statement: 2(m 1) = m 2 + m 3 reason: substitution property of equality

The coordinates r(1, -3), s(3, -1) t(5, -7) form what type of polygon? a right triangle an acute triangle an equilateral triangle an obtuse triangle