Answer:
x = 7
Explanation:
Intersecting secants theorem:
When two secants intersect outside the circle, the product of their segments are equal.
(3x + 15) * 15 = (x+20) * 20
3x * 15 + 15*15 = x*20 + 20*20 {Distributive property}
45x + 225 = 20x + 400
Subtract 225 from both sides,
45x = 20x + 400 - 225
45x = 20x + 175
Subtract 20x from both sides,
45x - 20x = 175
25x = 175
Divide both sides by 25,
x = 175 ÷ 25
