He measure of angle AFB = 78°

A. 78°

Step-by-step explanation:

From looking at the diagram, ∠DFE shares point F and line EB with ∠AFB. As a result, these two angles are adjacent to each other. That also means that the measures are also the same. That would mean ∠DFE is also 78°, so A is correct.

its not b

step-by-step explanation:

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,