(A) Bella's TV ratio of sides: 36"/27" = 1.333...
Lenny's: 52"/29.25" = 1.777...
Bella's and Lenny's TVs are NOT similar - their side ratios are different. Bella's is 4:3 while Lenny's is close to 16:9.
(B) Bella's TV has an exact ratio of 4:3 (36/27=4/3) and so is the older type.
Lenny's TV has a ratio of 52"/29.25". Divide both 52 and 29.25 by 3.25 to get 16/9, or 16:9. So Lenny's is the newer type.