Two factory plants are making TV panels. Yesterday, Plant A produced twice as many panels as Plant B. 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 two plants together produced 990 defective panels?

Question

Two factory plants are making TV panels. Yesterday, Plant A produced twice as many panels as Plant B. 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 two plants together produced  990  defective panels?

anonymous · Answer

lets call the amount in plant B say $x$ so the amount in plant A was double that $2x$

anonymous · Answer

5 % of the panels in B is $.05x$ and 2% of the panels in A are $.02\times 2x$ and you know that the total is $990$ so solve 
$$.05x+.04x=990$$