12x/5 = 18 i have no idea what x is

12x/5 = 18 
Multiply 5 on both sides
12x=90
Divide 12 on both sides
Final 90/12 or 7 6/12 or 7 1/2 or 7.5 *All answers are equivalent to each other.

#1. simplify x/5
(12∗x/5)-18=0
#2. 18=18/1=18∗5/5
combine them 
12x-(18∗5)/5=12x-90/5
#3. Pull out like factors 
   12x - 90  =   6 • (2x - 15)
6 • (2x - 15) /5= 0 
6•(2x-15)/5 • 5 = 0 • 5 
The equation now takes the shape    6  •  (2x-15)  = 0
#4.  Solve  :    2x-15 = 0 

 Add  15  to both of the sides of the equation 
                      2x = 15 
Divide both sides of the equation by 2
                     x = 15/2 = 7.500 

Intersecting secant-tangent theorem states that if a tangent segment and a secant segment are drawn to a circle from an exterior point, then the square of the measure of the tangent segment is equal to the product of the measures of the secant segment and its external secant segment.so to break it down: 1. pq acts as the tangent and ps as the secant with an intersection at p.sr = 21rp = 3x + 3pq = 4x + 4following to equation: tangent squared = the two segments multiplied by each otherso (4x + 4) ^ 2 = (3x + 3) • (21) simplifies to 16x^2 - 31x - 47 = 0 or (16x - 47)(x + 1) x = -1 or x = 47/162. pq acts as the tangent and ps as the secant with an intersection at p (again! )sr = 16rp = xpq = 15(15) ^ 2 = 16 • x225 = 16xx = 225/163. the interesting chords are proportional to each other so a ratio is possible to set up: ap dp 10 3 + x = = —— = pc pb 8 xcross multiple to get 10x = (3 + x)(8)x = 12