Please help, basic algebra.
Find the value of x

Which of the fallowing best completes the sequence 5,10,15, a) 30 b) 22 c)25 d)35

Which of the symbols correctly relates the two numbers below check all that apply 6? 6

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