The answer will depend on which country you are posting in and where the destination is. Also, in some countries, the nature of the contents will affect the postage (eg printed matter).
13 - 10% = 13 x (1 - (10/100)) = 13 x 0.9 = 11.7
The cost of postage depends on how much it weighs and the country where you are mailing it and its destination.
If: -3-x = 10 Then: x = -13
x + 3 + 10 = x + 13
The equation:3 x 2 + 5 x 2 - 13 - 10 / 2= (3 x 2) + (5 x 2) - 13 - (10 / 2)= 6 + 10 - 13 - 5= -2
depends on how many sheets u put inside..
At least 94 cents (two Forever stamps), and possibly more depending on weight.
13 - 10% = 13 x (1 - (10/100)) = 13 x 0.9 = 11.7
The cost of postage depends on how much it weighs and the country where you are mailing it and its destination.
If: -3-x = 10 Then: x = -13
(9/13) / (10/13) =(9/13) x (13/10) =9/10
If: -3-x = 10 Then: x = -13
This would move you letter into the "Flat Class" and can be mailed via 1st class as long as it weighs under 15oz. Your price would be about $.90.
x + 3 + 10 = x + 13
The equation:3 x 2 + 5 x 2 - 13 - 10 / 2= (3 x 2) + (5 x 2) - 13 - (10 / 2)= 6 + 10 - 13 - 5= -2
Over 9000.
13 > -10 + x/4 if 23 > x/4 if 92 > x that is, when x < 92