4)

x-(1 5/7-1/3)=-1 2/7÷0.5

x-(1 15/21 - 7/21) = -9/7 * 2/1

x - 1 8/21 = -18/7

x = -18/7 + 1 8/21

x = -18/7 + 29/21

x = -54/21 + 29/21

x = -25/21

x = -1 4/21

3)

-3/7y=-6/7×2.5

-3/7y = -6/7 * 5/2

-3/7y = -15/7

y = -15/7 *(-7/2)

y = 15/2

y = 7,5