The dimensions of a room are 12.5 m by 9 m by 7 m.

Given Length of the room = 12.5 m

Breadth of the room = 9 m

Height of the room = 7 m

Therefore, total surface area of the four walls = 2(l + b) * h

= 2(12.5 + 9) * 7

$=301 \mathrm{~m}^{2}$

Area of 2 doors = 2(2.5 *1.2)

$=6 \mathrm{~m}^{2}$

Area of 4 windows = 4 (1.5*1)

$=6 \mathrm{~m}^{2}$

Area to be painted on 4 walls = 301 - (6 + 6)

= 301 - 12

$=289 \mathrm{~m}^{2}$

Therefore, Cost of painting = 289 * 3.50

= Rs. 1011.5