Вычислите: 1/2-2/5-x=0; 3/7+5/21+x=2/3

Question

Вычислите: 1/2-2/5-x=0; 3/7+5/21+x=2/3

Answer 1

1/2 - 2/5 = x
5/10 - 4/10 = x
x = 1/10 = 0,1
3/7+5/21+x=2/3
14/21 - 9/21 - 5/21 = x
x=0