Let "x" represent the number of tv panels produced by plant B.
If plant A produced twice as many as plant B, then "2x" represents the number of tv panels produced by plant A.
For plant A, 4% of the panels were defective, to determine an expression that represents the number of defective panels, you have to multiply the amount produced by plant A by 0.04:

The expression "0.08x" represents the number of defective panels produced by plant A.
For plant B, 3% of the panels produced were defective, to obtain an expression that represents the number of defective panels, you have to multiply the production of plant B by 0.03:

The expression "0.03x" represents the number of defective panels produces by plant B.
Both plants together produced 770 defective panels, you can write this as:

From this equation, you can determine the value of x:
-Add both x-terms

-Divide both sides by 0.11

x=7000 → So plant B produces 7000 tv panels.