Solution 12176: Using the Numeric Solver on the TI-89 Family, TI-92 Family, and Voyage™ 200 Graphing Calculators.
How can I solve an equation on the TI-89 family, TI-92 family, and Voyage 200 graphing calculators?
The instructions below detail how to store an equation or formula using the numeric solver on the TI-89 family, TI-92 family, and Voyage 200.
Example: Store 30=5X and solve for X.
1) Press [APPS]  if the Apps Desktop is turned off. If the Apps Desktop is on, press [APPS] and select Numeric Solver.
2) At eqn: press   [=]  [X] [ENTER].
3) Move the cursor to the unknown variable and press [F2].
The displayed answer will show 6.
Please see the TI-89 family, TI-92 family and Voyage 200 guidebooks for additional information.