CPhill

(x + 2y + 2) + (x + y + 2) + (2x + y + 4)    collect like terms

 [ x + x + 2x ]  + [ 2y + y + y ]   + [ 2 + 2 + 4 ]  =

4x + 4y + 8

[m/5] * t   =

[2/5] * 876 =   1752 / 5  =  350.4

26 + (–3) ∙ (–8)

26 +  24   =

50     

Remember.....two negatives multiplied together gives a positive......

Here's the first one

Let x be the number of  25 centavo coins

And   2x - 9  = the number of 5 peso coins.....and a peso is worth 100 centavos.....so 5 pesos = 500 centavos

And 129.25 pesos = 12925 centavos....and we have....

25x +  500 (2x - 9)  = 12925     simplify

25x + 1000x - 4500 = 12925     

1025x =  17425    divide both sides by 1025

x = 17        this is the number of 25 centavo coins

2(17)  - 9   =  34 - 9   = 25  this is the number of 5 peso coins

4( 2 * 3)   = 24sq ft

And

2(2 * 2)  = 8 sq ft

So he needs 32 sq ft in total.....and there are 32 sq ft in one sheet.....so....he only needs one

Let W be the weight of the lighter dog   and 2W   = the weight of the heavier....so...

W + 2w  = 60   smplify

3W  = 60     divide both sides by 3

W = 20 lbs  = the lighter dog

2w =  2(20)  = 40 lbs.  = weight of heavier dog

Here's 6

L = 3W     original  area =  L * W   =  3W*W =   3W^2

[W - 1] [ L + 3] = 3W^2 + 72

[ W - 1] [ 3W + 3]  = 3W^2 + 72

3W^2  - 3W + 3W - 3   = 3W^2 + 72    

3W^2  - 3  = 3W^2 + 72         and this has no answer......(????)

Here's 15

Call the first angle x

The second = 2x + 10

The third = 5[2x + 10] - 10    and we have

x + 2x + 10 + 5[2x + 10] - 10  = 180    simplify

x + 2x + 10 + 10x + 50 - 10   = 180

13x + 50  = 180     subtract 50 from both sides

13x  =  130    divide both sides by 13    and x  = 10    and this is the first angle

2(10) + 10   = 30    and this is the second

5[30] - 10   = 140    and this is the third

Here's 14

Call the smallest angle, x

The second = 2x

The third = 3x

And we have

x + 2x + 3x  = 180

6x = 180     divide both sides by 6

x = 30

2x = 60

3x = 90

Here's 12

The original area = s^2

So

[s + 2] [s + 2 ]  = s^2 + 28   simplify

s^2 + 4s + 4  = s^2 + 28     subtract s^2 from both sides

4s + 4  = 28      subtract 4 from both sides

4s  = 24    divide both sides by  4

s = 6 cm    this is the side of the original square....and the original perimeter was 4 times this = 24 cm