Question 706327
I'm solving {{{(-1/4)t>=4}}}
Multiplying everything (both sides of the inequality sign) times as positive number
results in an equivalent inequality, so multiplying times 4 we would get
{{{-t>=16}}}
Changing the sign of the expressions on both sides
(it is exactly the same as multiplying times {{{(-1)}}})
flips everything to the other side of zero,
so to get an equivalent inequality, you also have to flip the inequality sign, so
{{{-t>=16}}} --> {{{highlight(t<=-16)}}}
I could have done both steps in one by multiplying times {{{(-4)}}}.
It's the same thing, but harder to visualize.
 
The "properties" are what common sense tells you.
It's what makes sense in real world situations.
Math does not require to memorize much.
You just have know meaning of some symbols and definitions,
and think of what it means,
not by "juggling words", or invoking "voodoo rules", but by using ideas.
With inequalities you can add the same number to both sides and you get an equivalent inequality
You can subtract the same number from both sides with the same result (subtracting is just adding the opposite number).
You can multiply/divide by a positive number both sides and get an equivalent inequality.
However, multiplying/dividing by a negative number requires flipping the inequality sign.