If you have multiple equations with multiple variables, you can either do clever substitutions, or turn it into a matrix on which you can perform linear combinations or multiplications (Gauss elimination)
1 1 1 1
2 1 -1 8
1 -1 1 -5
(note how the above 3 rows represent the 3 equations, just got rid of the variables, plus sign and equals sign)
subtract row1 from row3, that eliminates x and z from row 3.
1 1 1 1
2 1 -1 8
0 -2 0 -6
divide row3 by -2, that will give y a factor of 1
1 1 1 1
2 1 -1 8
0 1 0 3
The last row now says y=3
Step-by-step explanation:
I just answered this ...
the first thing we notice : the quadrilateral has 2 pairs of equally long sides with 2 angles being openly 90°.
so, we are dealing with a rectangle here.
we know that one pair of the sides (NK = LM) are 24 cm long.
and we know that KL:LM = 3:4.
that means that the pair KL = MN are the shorter sides of the rectangle. and their length is according to the ratio 3/4 of NK=LM.
3/4 × 24 = 18 cm
the area of that rectangle is therefore
18 × 24 = 432 cm²
<span>86.23 Should be the correct answer =)</span>
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❖ A number y increased by 5 is at least -21.
❖ First, if you come across the word "increased" it means we
"increase" a number, or add something to that number, like
y increased by 5 
Now, we are also given that this expression is at least -21, which means it can't be -21; it can be -21 or it can be greater than -21.
So we have
<em>Solving for y</em>
<em></em>
- Subtract 5 on both sides:-
So the values of y greater than or equal to -26 will make this inequality true.
<h3>Good luck with your studies.</h3>
