Question

a number is decreased by 3 is at least four times the number

Answer 1

n-3 >/= 4 n ????
3 n </= -3
n </= -1
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check, try n = -2
-2 -3 >/= 4 (-2)
-5 >/= -8
yes, -5 is to the right of -8 on number line.