Angles that are congruent and supplementary must be
a. acute angles.
b. obtuse angles.
c. straight angles.
d. right angles.

d. right angles.

Step-by-step explanation:

Let a and b be two angles which are congruent and supplementary

Then a=b [congruent]

And

Hence, the angles  that are congruent and supplementary must be right angles.

hello :

by applying the distributive property :

6 × 4.3 = 6 × ( 4 + 0.3 )

            =   (6 ×   4) + (6 ×   0.3)

            = 24 + 1.8

6 × 4.3 = 25.8