CPhill

-x - y = -8       →    x + y  = 8    →   y  = 8 - x     (1)

x + 3y  = 16       (2)

Sub  (1)  into (2) 

x + 3( 8 - x )   =  16

x + 24 - 3x  = 16

-2x  + 24  = 16      subtract  24 from both sides

-2x = -8    divide by -2

x  = 4

And using (1)  ...... y  = 8 - x   →  y  = 8 - 4   y   =  4

So  { x, y }   =  { 4 , 4 }

-(3y+22) + 4y =106   simplify

-3y - 66 + 4y  =  106

y - 66 = 106      add 66 to each side

y = 172

0.617=1-(1/x^0.4)   rearrange as

1/ x^0.4  = 1 - 0.617

1 / x^0.4  = 0.383      and we can write

x^0.4  = 1 /0.383          [   0.4  = 2/5  ]

x^(2/5)  = 1 / 0.383

[x^(2/5)]^(5/2)  = [ 1/ 0.383 ] ^(5/2)

x  = [ 1 / 0.383]^(5/2)  ≈ 11.0155

Looks like you did anyway, Melody.......LOL!!!!

Area_cube  =   6 * [side length ]^2

2x^3+x^2+23  →   6x^2  + 2x

96/4  =  24     ........not a mixed number......!!!!

Original Selling price  = €250 (1.20)  = €300

Selling price after 15% discount   =   €300 * .85  = €255

%profit on the original cost  =  [255 - 250] / 250 = .02  = 2%

d₂  = √[ 75^2 + 10^2]  = 75.66 m

d₁ =  √[ 55^2 + 5^2]  =   52.23 m

d₂ - d₁  ≈ 23.43 m ≈ 23.4 m   farther

distance apart  = √ [ ( 75 - 55)^2 + (10 - 5)^2]   =  √ [ 20^2 + 5^2 ] =

√[ 425]  ≈ 20.6 m

Neither

Hypotenuse  =  √ [ opp^2 + adj^2 ]