Question 201753
[ 5-3x] +3 <= 7
.
[5-3x] <= 4
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(5-3x) <= +4,,,,,,,(5-3x) >= -4
.
-3x <= -1,,,,,,,,,,,,-3x >= -9
.
x >= 1/3,,,,,,,,,,,,,,,x <= 3 
.
check
x less  than  1/3,,,test  point = 0, [5] +3 <= 7,,,8<=7,,,not  true
.
x >=1/3,and x<=3,,test  point = 2,,[5-6] +3 <= 7,,4<=7,,,,ok
.
x>3,,,,,test  point = 4,,,[ 5-12] +3 <=7,,7+3<=7,,,,not  true