First, we have
s1/r1 = s2/r2
The question also states the fact that
s/2πr = θ/360°
Rearranging the second equation, we have
s/r = 2πθ/360°
Then we substitute it to the first equation
s1/r1 = 2πθ1/360°
s2/r2 = 2πθ2/360°
which is now
2πθ1/360° = 2πθ2/360°
By equating both sides, 2π and 360° will be cancelled, therefore leaving
θ1 = θ2
As given m is a midpoint of ab. So am is half of ab.
So we can write

As given am = 3x+3 , ab = 8x - 6.
So





So x = 6.
So length of am = 3x+3 = 3*6 + 3 = 21
267 x 0.02 = 5.34
267 + 5.34 = 272.34
267 x 0.08 = 21.36
267 - 21.36 = 245.64
267 + 272.34 + 245.64 = $784.98