We know that
When two chords intersect each other inside a circle, the products of their segments are equal (Intersecting Chord Theorem)
so
AE*EB=DE*EF-----> EB=DE*EF/AE
AE=4 in
DE=12 in
EF=8 in
EB=?
EB=DE*EF/AE
EB=12*8/4-----> EB=24 in
Use Pythagoras theorem:
a^2 = b^2 + c^2
-15^2 + 18^2 = a^2
a^2 = 99
a = root of 99
The coordinates of r is ( 4, -1 )
4.8 pounds, set it up as 4 over 10 times x over 12, to find x multiply 4 by 12, and divide by ten. The result is 4.8