arithmetic
posted by niraj .
The base of a solid right prism is a triangle whose sides are 9cm,12cm and 15 cm.the total surface area of the prism.

not enough information, you didn't give the height of the prism.
Since the base is a rightangled triange, (9^2 + 12^2= 15^2),
the area of the base is (1/2)(9)(12) = 54 cm^2
Once you know the height h, the total surface area would be
2(54) + 9h + 12h + 15h