Пошаговое объяснение:

2.

2) y-5 3/4= -6 5/8

y= -6 5/8+5 3/4

y= -6 5/8+5 6/8

y= -53/8+46/8

y= -7/8

3.

1) 12-20+11+18+6-10=

=47-30=

=17

2) 3 5/12+1 1/3-3/8+2 1/4-5 5/6=

=41/12+4/3-3/8+9/4-35/6=

=82/24+32/24-9/24+54/24-140/24=

=(168-149)/24=

=19/24