a) (x + 15) - 8 = 17
x + 15 - 8 = 17
x + 7 = 17
x = 17 - 7
x = 10
Проверка:
(10 + 15) - 8 = 17
25 - 8 = 17
17 = 17
б) (24 + x) - 21 = 10
24 + x - 21 = 10
x + 3 = 10
x = 10 - 3
x = 7
Проверка:
(24 + 7) - 21 = 10
31 - 21 = 10
10 = 10
в) (45 - y) + 18 = 58
45 - y + 18 = 58
-y + 63 = 58
-y = 58 - 63
-y = -5
y = 5
Проверка:
(45 - 5) + 18 = 58
40 + 18 = 58
58 = 58
г) (y - 35) + 12 = 32
y - 35 + 12 = 32
y - 23 = 32
y = 32 + 23
y = 55
Проверка:
(55 - 35) + 12 = 32
20 + 12 = 32
32 = 32
д) 56 - (x + 12) = 24
56 - x - 12 = 24
44 - x = 24
-x = 24 - 44
-x = -20
x = 20
Проверка:
56 - (20 + 12) = 24
56 - 32 = 24
24 = 24
е) 55 - (x - 15) = 30
55 - x + 15 = 30
70 - x = 30
-x = 30 - 70
-x = -40
x = 40
Проверка:
55 - (40 - 15) = 30
55 - 25 = 30
30 = 30