Tessellated Pictures

[BMAD]

I have lots of photo prints, in two sizes: (a) 4 x 6 inches, and (b) 5 x 7 inches. I put photos up on the wall, each one can be vertical or horizontal, so that they tile into a big rectangle (with no overlapping or cutting, of course).

i) Prove I can't make a 19 x 19-inch "photo-square."

II) Show me how to tile the 29 x 29 photo-square.

[TimeSpaceLightForce]

a) 19x19=361=24x+35y ; y=(361-24x)/35 x limit=11,none integer for x{1,2,...11}

b) 29x29=841=24x+35y ; y=(841-24x)/35 x=19 y=11 ,no.of short pic side = no of long pic side for the square side