Answer:
If Brianna's (I'll call her Bri in this situation) teacher says 3r + 5 and 4r are equal, you should definatly start by adding the 'r' value to the 3, which would be 8 afterwards. Bri is then incorrect because 4+5=9, and 9 is greater than 8, so Bri is wrong :'(...
Have a good day fellow lad,
AshlynnXOXO
Perimeter = x + 5x - 2 + 7x - 4
= 13x - 6 meters answer
Try going through the formula which is 2 pi r
so 2*3.14*7
B - 3A = 2
3B - 6A = 12
(2)B - (6)A =4
3B - 6A = 12
Subtract
-B = -8
B = 8
Plugin 8 for B
8 - 3A = 2
8 = 3A + 2
6 = 3A
2 = A
(Double checking)
3(8) - 6A = 12
-6A = 12-24 = -12
- 6A = -12
Divide by -6
A= 2
It works
A = 2. B = 8. Hope this helps