How to use ti 89 with a problem like "-(3x+1)-(4x-7)=4-(3x+2)'

You're missing a parentheses.

If you mean e^(ln(177/149)/7)*26 then press
2ND [e^x] ( LN ( 1 7 7 / 1 4 9 ) / 7 ) right-arrow * 2 6 ENTER
if you're in the MATHPRINT mode. In the CLASSIC mode press
2ND [e^x] LN 1 7 7 / 1 4 9 ) / 7 ) * 2 6 ENTER

7 LOG / ( 6 * 7 LOG - 2 LOG ) =

On a TI-30XA the EE key is just above the 7 key.

On a TI-30XIIS the EE is the shifted function of the key just above the 7 key.

You can download the manual from: http://education.ti.com/downloads/guidebooks/graphing/89ti/TI-89_Guidebook_EN.pdf
On page 79, you will find:
Find log (x,b). You can enter "log" on the entry line by typing LOG on the keyboard, or by pressing the key with the diamond and then 7.
Press [diamond] 7 X , [alpha] b ) [ENTER]

You can get the software for the ti on the link below.

http://education.ti.com/educationportal/sites/US/productDetail/us_ti_connect.html?subid=1&topid=41

http://education.ti.com/downloads/files/83plus/TI84Plus_OS.8Xu

Good Luck and please rate 4 thumbs up for the free answer

Potentially, the batteries are very weak, and you might just need to change them out (4 AAA's). More likely, I think there is something defective with such a calculator. Depending upon how long ago you purchased it, it is possible of getting it replaced. The following is Texas Instruments service rep contact info from there website (as of: June 17th, 2010).

TI-Cares Customer Support Contact a TI-Cares Customer Support representative via e-mail or phone to order products, inquire about issues, or ask general questions about TI education technology.

1-800-TI-CARES (800-842-2737)
Monday - Thursday: 8 a.m. - 7 p.m. Central Time
Friday: 10 a.m. - 7 p.m. Central Time Contact TI-Cares Support

Pressing ( 7 / 8 ) + ( +<>- 2 / 7 ) = will produce the answer on the TI-30XA.

+<>- is the key to the right of the decimal point.

The comma key on the TI 84 SE is above the 7 key, and it is just left of (, right of x squared, and below SIN. thats where the "," key is. If you're asking something else, please clearify. My understanding is that you don't know where the comma key is.