I suppose <em>K</em> is the matrix

To compute det(<em>K</em>), you can use a simple cofactor expansion along the first row:

Area formula: L · W · H
Length: 0.5
Width: 5
Height: 5
Answer: 12.5²
(It's squared because 5√2 contains a square root.)
So first, we want to substitute in 15 to all the x variables.
So,
3x - 8y = 5
Becomes
3 * 15 - 8y = 5
Or,
45 - 8y = 5
So here, you can subtract 45 from both sides to move all like terms to one side.
-8y = 5 - 45
And then simplify:
-8y = -40
Then divide both sides by -8
y = 5
Answer:
Step-by-step explanation:
P = 2l + 2w
= 2(12) + 2(18)
= 24 + 36 = 60