6:(1/2+1/2) 12:(1/2+1/2+1/2+1/2). (1/5+1/5+1/5)•1/3. (2/7+2/7+2/7+2/7)•21/8

6 / (1/2 + 1/2) = 6/1 = 6
12 / (1/2 + 1/2 + 1/2 + 1/2) = 12/2 = 6
(1/5 + 1/5 + 1/5) • 1/3 = 3/5 * 1/3 = 3/15 = 1/3
(2/7 + 2/7 + 2/7 + 2/7) • 21/8 = 8/7 * 21/8 = 168/56 = 3

6:(1/2+1/2)=6:1=6
12:(1/2+1/2+1/2+1/2)=12:2=6
(1/5+1/5+1/5)*1/3=1/5
(2/7+2/7+2/7+2/7)*21/8=3