Answer
a) 1
b) $m_1=2.7X$ (from)
$m_2=1X$ (back)
Work Step by Step
a) Because X Ray images are shadows, the length of the image and length of the object have the same size, and magnification will be 1.
b) $m_1=\frac{h_1}{h_{o1}}=\frac{d_1+d_2}{d_1}=\frac{15cm+25cm}{15cm}=\frac{40cm}{15cm}=2.7X$
$m_2=\frac{h_1}{h_{o1}}=\frac{d_1+d_2}{d_1}=\frac{15cm}{15cm}=1X$