The answer is 91tvb now,tvbnow,bttvb2 U- H& ]% L( g& a
1 row 3x4+1x3=15tvb now,tvbnow,bttvb. G# n G) m- i" i" k" d6 e3 v
2 row 4x5+2x4=28
. F& K9 o. ~: n/ ^: @& G3 row 5x6+3x5=45
8 l+ C* k/ B, q1 t( j9 G, e. Ltvb now,tvbnow,bttvb4 row 6x7+4x6=66
% B$ X" m$ w/ ]* k5 row 7x8+5x7=91  |