Which multiplication could be used to solve 45 = n?

What is the number 321,000,000 in scientific notation? also what is the number? ?

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

1) prove that 731^3−631^3 is divisible by 100 2) prove that 99^3−74^3 is divisible by 25