408 *7=(400+8)*7=400*7+8*7=2000+56=2856
298*4=(300-2)*4=300*4-2*4=1200-8=1192
Вроде так)))
16 - 4²
64 - 8²
36 - 6²
400 - 20²
(6 1/7 - 5 3/4 ) : 11 + (3 3/4 - 1 5/6) : 1/6 = (6/7 - 15/4) : 11 + (9/4 - 5/6) : 1/6 = (24/28-105/28):11+(27/12-20/12):1/6= -81/(28*11)+(7*6)/12= 20.25/77+3.5 = 20.25/77+269.5/77=289.75/77