(5 intreg si 3 pe 5 + 1 intreg si 1 pe 3):(7 intreg si 7 pe 12-2 intreg si 1 pe 4)=
=(28/5+4/3) :(91/12-9/4)= (28x3+4x5)/15 :(91-9x3)/12=
=104/15 : 64/12 = 104/15 x 12/64 =13/15x12/8=13/5x 4/8= 13/5x1/2=13/10
104 64 8x13 12 8x13 x3x4 13 13
------ : ---- =-------- x ---- = ----------------- = ------- = -----
15 12 3x5 64 3x5x8x2x4 5x2 10