<span>B. It is the number of edges on one base plus 2.</span>
Y + 4x = 8
y = 8 - 4x
substitute 8 - 4x for y in the other equation.
5x + 2(8 - 4x) = 13
5x + 16 - 8x = 13
-3x = -3
x = 1
y = 8 - 4(1) = 4
The third one its already in order
3 = $9.81
1 = $?
To find this you have to do 9.81/3.
Hope this helps and have a nice day!!