Multiplying:
3(0.2x+0.4y) = 0.6x + 1.2y
(1.6x+2.8y)2 = 3.2x + 5.6y

Adding:
0.6x + 1.2y + 3.2x + 5.6y = 3.8x + 6.8y

Solving the equation:
0.8y + 1.4 = 0.4y - 2.6
0.8y - 0.4y = -2.6 - 1.4
0.4y = -4
y = -4 / 0.4
y = -10

Substitute y back into the equation:
3(0.2x + 0.4(-10)) + (1.6x + 2.8(-10))2 = -6
0.6x - 12 - 5.6x - 56 = -6
-5x - 68 = -6
-5x = 62
x = 62 / -5
x = -12.4

Therefore, x = -12.4 and y = -10.

Solving the second equation:
2 2/3x + 3 2/15 = 3 1/5x + 2 2/5
8/3x + 47/15 = 16/5x + 12/5
8/3x - 16/5x = 12/5 - 47/15
(40 - 48) / 15 = (36 - 141) / 75
-8/15 = -105/75
-8/15 = -7/5
5(-8) = -715
-40 = -105

The equation has no solution.

Solving the third equation:
(4 1/6y + 11 1/4) 4/15 = 2/3y + 5 2/3
(25/6 -10 + 45/4) 4/15 = 2/3 -10 + 17/3
(-50/3 + 45/4) 4/15 = -20/3 + 17/3
(-200/12 + 135/12) 4/15 = -3/3
(-65/12) * 4/15 = 14/3
-260 / 60 = 14/3
-13/3 = 14/3

The equation is not balanced.