the answer is 15
these chords are congruent because the radius of the circle are perpendicular to the them
so we can find EF by making an equation:
[tex]3x + 5 = x + 35 \\ 3x - x = 35 - 5 \\ 2x = 30 \\ x = \frac{30}{2} = 15 [/tex]
so EF is = 3(15)+5=50
good luck
