Which statement can be combined with its converse to form a true biconditional?

a. if an angle is a straight angle, then its sides are opposite rays.

b. if the measure of an angle is 30, then it is an acute angle.

c. if a ray is the perpendicular bisector of a segment, then the ray divides the segment into two congruent segments.

d. if two lines intersect, then the two lines are not skew.

This one is hard for me.

I choose : A

I hope that's help:)

mr. flanders’ class sold 47 doughnuts and   mr. rodriquez’s class sold 38 cartons of milk

step-by-step explanation:

let x be the number of doughnuts sold by mr. flanders’ class and y be the number of cartons sold by mr. rodriquez’s class.

1. together, the classes sold 85 items, then

x+y=85.

2. both classes earn earned $104.49 for their school. if doughnuts were sold for $1.35 each, then x doughnuts costed $1.35x. if cartons of milk were sold for $1.08 each, then y cartons costed $1.08y. hence,

1.35x+1.08y=104.49.

3. solve the system of two equations:

answer: .64

step-by-step explanation

set up the formula for standard deviation for this set of numbers, then simplify