Answer:
105cm
Step-by-step explanation:
Call the rat's height r, the cat's height c and the table height t.
The left part says that
(t + c) - (0 + r) = 120 = t + c - r
c - r = 120 - t
Right part says that (t + r) - (0 + c) = 90 = t + r - c
c - r = t - 90
120 - t = t - 90
2t = 210
t = 105
