1)
(120 : x - 3) : 2 = 6
120 : x - 3 = 12
120 : x = 15
x = 120 : 15
x = 8
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2)
4 * (85 : x + 3) = 32
85 : x + 3 = 8
85 : x = 5
x = 85 : 5
x = 17
============
3)
3 * (x : 6 - 7) = 18
x : 6 - 7 = 6
x : 6 = 13
x = 13 * 6
x = 78
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4)
x : 15 = 0,6
x = 0,6 * 15
x = 9