15. In the diagram AB is parallel to CD.
Calculate the value of a.
NOT TO
SCALE

Same-side interior angles, which are shown here, are supplementary, which means that they add up to 180 degrees.

5a + a = 180

6a = 180

a = 30 degrees

Hope this helps! :)

option (b) is correct

step-by-step explanation:

to find the solution of this system, we need to convert it into reduced row-echelon form. we have,

after applying row operations r2 -> r2/2 and r3 -> r3/3, we get,