1. Is the set closed or not closed under the operation? integers under addition

2. Is the set closed or not closed under the operation?
positive integers under multiplication

3. Is the set closed or not closed under the operation?
negative integers under multiplication

25/14 or 1.

step-by-step explanation:

the dots mean that it has infinitely more numbers behind it

80° is the measure of gh

step-by-step explanation:

circle f is congruent to circle j

we have two circle with center f and j.

both circles are congruent. the radius of the circle would be equal.

see the attachment for the circle.

we are given ∠efd ≅ ∠gjh

therefore, arc (ed) = arc (gh)     (∴ circle f is congruent to circle j)

but ∠dfe=80°=arc (ed)

therefore, arc (gh) = 80°

thus, 80° is the measure of gh