breadstickim01

Using basic subtraction I believe the answer would be 8x-1 

p = 3 + 2q 

r = 9 + p - p 

r = 9 

q = -2 + q - 2r 

0 = -2 + -2r 

2 = -2r 

r = -1 

There are 2 different r values , thus there is no solution to this system 

Use algebra and list the equations for each situation:

6 stamps situation : where x = number of friends 

6x + 5 

7 stamps situation : x = number of friends 

7x -2 

Set them to equal each other 

6x +5 = 7x -2 

solve : 

x = 7 

Thus he has 7 friends 

using y - 2x = 3 

We get that y = 2x + 3

Substitute that into the second equation 

-x = (2x+3) - 9 

-x = 2x - 6 

6 = 3x 

x = 2 

and 

y = 7 

1600/20 = 80 square feet per person

Now since they all do it at the same time then "

8/3 sq feet per minute therefore 

15 x 8/3 = 40 ft per minute 

1800 / 40 = 45 minutes 

for proportion problems always break down the answer into per __ unit , (small as possible)