Answer
$\int~E\cdot ds = 1.34\times 10^{-3}~V$
Work Step by Step
Note that the magnetic fields are in the opposite directions.
$\int~E\cdot ds = -\frac{d\Phi}{dt}$
$\int~E\cdot ds = -[(\pi~r_2^2)~\frac{dB}{dt} - (\pi~r_1^2~\frac{dB}{dt})]$
$\int~E\cdot ds = -[(\pi)~(0.30~m)^2~(-8.50~mT/s) -(\pi)~(0.20~m)^2~(-8.50~mT/s)]$
$\int~E\cdot ds = 1.34\times 10^{-3}~V$
