The two square pyramids are similar. Find the total volume of both pyramids if the ratio of their surface areas is. 9/16

If the ratio of surface area is 9/16, then the ratio of linear dimensions is sqrt (9/16) = 3/4, and the ratio of the volumes is (3/4) ^3=27/81.

Therefore the total volume = (1+27/64) * volume of the larger pyramid

= (91/64) * volume of the larger pyramid.