221,000,000,000,000,000,000 in scientific notation

Which statements regarding efg are true? check all that apply.

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

Which of the following questions describes the equation g + (-4) = -5? a)what number, when added to negative four, is equal to negative five? b)what number, when added to negative five, is equal to negative four? c)what number, when subtracted from negative four, is equal to negative five? d)what number, when subtracted from negative five, is equal to negative four?