Two factory plants are making tv panels. yesterday, plant a produced 12,000 panels. two percent of the panels from plant a and 5% of the panels from plant b were defective. how many panels did plant b produce, if the overall percentage of defective panels from the two plants was 3% ?

Let x be the number of television panels that the Company B produced. It is stated in this item that 5% of these panels are defective. The number of defective panels from Company B is therefore equal to 0.05x. 

With the representation above, the total number of panels produced by the two companies is equal to 12000 + x. The percentage of total defective panels to the total panels produced can be expressed through the equation,
     ((12000)(0.02) + 0.05x) / (12000+x))(100) = 3

Dividing the equation by 100
   (240+0.05x)/(12000+x) = 0.03

Cross-multiplying the denominator of the left-hand side to the right hand side of the equation,
   240 + 0.05x = 360 + 0.03x

Transposing like terms,
    0.02x = 120

Dividing the equation by 0.02.
   x = 6000

ANSWER: The number of tv panels produced by Company B is 6000.