Which of the following are proper units of mass in the metric system ounce kilogram meter milligram

kilogram and milligram are proper units of mass in the metric system . Anything with the suffix -gram is a mass measurement  Hope this helps!

true statements:

a) x + y = y + x   ⇒ commutative property of addition

b) (x * y) * z = x * (y * z) ⇒ associative property of multiplication

d) (x + y) + z = x + (y + z) ⇒ associative property of addition

false statements:

c) x - y = y - x   should be: x - y = - y + x

e) (x - y) - z = x - (y - z) should be: (x - y) - z = x - (y + z)

step-by-step explanation:

-4

step-by-step explanation:

(-4+8)=-(4-8)=-8+4=-4