решите уравнения
x-2/3=5/6
a×0,4=4/15
x-5/8=5/8
9/10÷c=3/20

1)x-2/3=5/6

x=5/6+2/3

x=3/2

2)a×0,4=4/15

0,4a=4/15

a=2/3

3)x-5/8=5/8

x=5/8+5/8

x=5/4

4)9/10÷c=3/20

9/10×1/c=3/20

9/10c=3/20

180=30c

30c=180

c=6

x - 2/3 = 5/6х = 5/6 + 2/3 х = 5/6 + 4/6 х = 9/6 = 1 3/6 = 1 1/2 a × 0,4 = 4/150,4а = 4/15 |÷0,4 0,4а ÷ 0,4 = 4/15 ÷ 4/10 а = 4/15 × 10/4 а = 4/15 × 5/2 а = 2/3 = 0,6 x - 5/8 = 5/8х = 5/8 + 5/8 х = 10/8 = 5/4 = 1 1/4 9/10 ÷ с = 3/20 9/10 × 1/с = 3/20 9/10с = 3/20 9×20 = 3×10 180с = 30 с = 6