Which expression is equivalent to - 10 + (-40) + (-90) ?

D.-10 + (-90) + (-40)

S. - 10 - (40-90)

B. - (10-40) + (-90)

C. 10+40+90

It is easy, answer D.

If you see, on answer D commutative property is applied.

-10 - 40 - 90 = - 140

-10 - 90 - 40 = - 140

It is always - 140

It can't be S because - 10 - (40-90) = - 10 - (-50) = - 10 + 50 = 40

It can't be B because - (10-40) - 90 = - (-30) - 90 = + 30 - 90 = - 60

It can't be C because it would give + 140

So, answer D is right.