Given:
Fact 1: During contract negotiations, BB’s sales representative promised that the system was “A-1” and “perfect.”
Fact 2: The written contract, which the parties later signed, disclaimed all warranties, express and implied.
Fact 3: After installation the computer produced only random numbers and letters, rather than the desired accounting information
The express warranty is given in Fact 1 where the Sales Rep promised that the system was "A-1" and "perfect". There is a breach in express warranty here IF the written contract also expresses the same promises.
However, the written contract disclaimed all warranties, express and implied. AND BOTH PARTIES SIGNED THIS CONTRACT. It implies that the buyer has read through the contract and has agreed with what is written in the contract. Thus, they can't file a suit against BB for breaching an express warranty since the written and signed contract has already disclaimed all warranties.