Answer:
x = 7
Explanation:
Given 2 secants from an external point to the circle, then
The product of the external part and the entire of one secant is equal to the product of the external part and the entire of the other secant, that is
5(5 + x) = 6(6 + 4) ← distribute parenthesis on both sides
25 + 5x = 6 × 10
25 + 5x = 60 ( subtract 25 from both sides )
5x = 35 ( divide both sides by 5 )
x = 7