Mathematics

Problem

x_1, x_2, \dots, x_n

and

\frac{1}{h_1}, \frac{1}{h_2}, \dots, \frac{1}{h_n}

are two A.P.s such that

x_3 = h_2 = 8

and

x_8 = h_7 = 20

, then

x_5 \cdot h_{10}

equals (a) 2560 (b) 2650 (c) 3200 (d) 1600