1) 1,1x - 2 1/2 = 3/5x
1,1x - 3/5x = 2 1/2
1,1x - 0,6x = 2 1/2
0,5x = 2 1/2
0,5x = 2,5
x = 2,5 : 0,5
x = 5
2) 6,75x = 2 1/4x - 9
6,75x - 2 1/4x = -9
6,75x - 2,25x = -9
4,5x = -9
x = -9 : 4,5
x = -2
3) 16 - 9 1/2y = 3y + 21
16 - 21 = 9 1/2y + 3y
-5 = 12,5 y
y = -5 : 12,5
y = -0,4
4) 1 1/4y + 7,5 = 5y
1,25y - 5y = -7,5
-3,75y = -7,5
y = -7,5 : (-3,75)
y = 2
5) 0,5 x - 7 = -2/3x
0,5x + 2/3x = 7
1 1/6x = 7
x = 7 : 1 1/6
x = 6
6) 6y - 2 4/5 = 2,5y
6y - 2,5y = 2 4/5
3,5y = 2 4/5
y = 2,8 : 3,5
y = 0,8