robert bought 8 dollars worth of 6 cent stamps and 8 cent stamps. He has a total of 110 stamps. Find how many of each stamp he has.

Guest Apr 29, 2015

#1**+5 **

Let x be the number of 6 cent stamps. Then 110 - x equals the number of 8 cent stamps. So we have... (in cents).....

6x + 8(110 - x) = 800 simplify

6x + 880 - 8x = 800

-2x + 880 = 800 subtract 880 from both sides

-2x = - 80 divide both sides by -2

x = 40 and that's the nimber of 6 cent stamps

And (110 - 40) =70 and that's the number of 8 cent stamps

CPhill
Apr 29, 2015

#2**+5 **

Cphill thats an excellent answer (obviously...as always)...but as usual the problem is i dont get this step...i mena cna you tell me why you did it like this....explain....

6x + 8(110 - x) = 800 simplify

rosala
Apr 29, 2015

#3**+5 **

Rosala.....

Notice that the cost of each stamp type times the number of them can be written as :

6 cents x the number of 6 cent stamps + 8 cents x the number of 8 cent stamps = the total cost (8.00 or 800 cents)

Or simply

6x + 8(110 - x) = 800 [I'm expressing everything in terms of cents in this equation ]

Does that make sense ????

CPhill
Apr 29, 2015