Which set of measurements could be the interior angle measures of a triangle?

Which expression demonstrates the use of the commutative property of addition in the first step of simplifying the expression (-1+i)+(21+5i)+0

Present age of man is 45 years, 5 years back his age was 4 times age of his son what is present age of his son?

Write as a product: ac^2–ad+c^3–cd–bc^2+bd