Question

Реши уравнения: 17-х=8; 13-а=9; 90-с=60

Answer 1

$17 - x = 8 \\ 17 - 8 = x \\ x = 9$
$13 - a = 9 \\ 13 - 9 = a \\ a = 4$
$90 - c = 60 \\ 90 - 60 = c \\ c = 30$

Answer 2

17-x=8
x=17-8
x=9
Проверка:17-9=8
8=8
13-а=9
а=13-9
а=4
Проверка:13-4=9
9=9
90-с=60
с=90-60
с=30
Проверка:90-30=60
60=60
Вот.