89+(17-x)=81
89 + 17 – x = 81
– x = 81 – 17 – 89
-x = -25
x = 25
х -13 = 513
х = 513+13
х = 526
157-(x+7)=130
157 – x – 7 = 130
– x = 130 + 7 – 157
-x = -20
x = 20
89+(17-x)=81
89 + 17 – x = 81
– x = 81 – 17 – 89
-x = -25
x = 25
х -13 = 513
х = 513+13
х = 526
157-(x+7)=130
157 – x – 7 = 130
– x = 130 + 7 – 157
-x = -20
x = 20