Problems using solve function for linear system of equations

Hey guys im having trouble using the solve function. I need it to return values for variables within a certain range but for some reason im getting negative values for my P1 P2 and P3.

How can i tell matlab that the P values must be between:

0<P1<270

0<P2<200

0<P3<200

Answer 1

[Alex Mcaulley]

Use assume function before solve:

assume(0 < p1 < 270)
assume(0 < p2 < 270)
assume(0 < p3 < 270)