The answer is 1 day because if it takes Doug 3 days by himself and if his son helps him and it takes 2 days with the both of them that means it would only take Doug's son 1 day.
A square has four 90° angles. So:
15x-30=90 add 30 to both sides
15x=120 divide both sides by 15
x=8°
Yes, we can prove that the given figure is a parallelogram.
From the given figure, we can see that the given quadrilateral opposite angles and congruent. And we know that if a quadrilateral has two opposite angles congruent, then the quadrilateral is a parallelogram.
Therefore, we can say that the given figure is a parallelogram.
From the given options, second option is correct.
Therefore, the correct option is:-
Yes, opposite angles are congruent.