Пошаговое объяснение:

(1,25+1/6)×2,4=(1 1/4+1/6)×2,4=

=(5/4+1/6)×2,4=(15+2)/12×2,4=

=17/12×2 2/5=17/12×12/5=17/5= 3 2/5=3,4

(7,6-4 3/4):1,9=(7,6-4,75):1,9=2,85:1,9=1,5

(5,4-2 1/3):7 2/3=(5 2/5-7/3):23/3=

=(27/5-7/3):23/3=(81-35)/15×3/23=

=46/15×3/23=2/5=0,4