Simplify 2√7- \(\frac{14}{√7} + \frac{7}{√21}\)

If 4x+2y=16 and 6x-2y=4 , find the value of (y-x).

 In the diagram, ∠ABC and ∠BCD are right angles, ∠BAD = t and ∠EDF = 70°. Find the value of t.

The sum of the interior angles of a regular polygon with k sides is (3k-10) right angles. Find the size of the exterior angle?

make u the subject in x =\(\frac{2u-3}{3u + 2}\)