Pre Algebra
posted by Lily .
Find the missing length, when the perimeter is 9x+11.
They give me 2 lengths:
2x+3 and 3x+1 how could I find the missing length x?
would I add 2x+3+3x+1? and then subtract the total by 9x+11?

Is your figure a triangle?
Are the three sides 2x+3, 3x+1, and x ??
If so, then
2x+3 + 3x+1 + x = 9x+11
6x  9x = 11  4
x = 7/3 ..... makes no sense
OK, try something different.
let the third side be y
then 2x+3 + 3x+1 + y = 9x+11
y = 9x5x+114
y = 4x+7 
ohh, ok, thank you so much :)