A certain Sky Blue paint contains 10 percent blue pigment and 90 percent red pigment by weight. A certain green paint contains 70 percent blue pigment and 30 percent yellow pigment. When these paints are mixed to produce a brown paint, the brown paint contains 40 percent blue pigment. If the brown paint weighs 10 grams, then the red pigment contributes how many grams of that weight?
Choose the correct option
A) 1.5	B) 2.5	C) 3.5	D) 4.5	E) 5.5

Rationale: 10 grams of combined mixture and 40 % blue pigment means that the mixtures were mixed 50 % each . thus 5 grams a piece . out of the 5 grams of the dark blue paint , 60 % is red . therefore , 5 * . 9 = 4.5 grams of red pigment
Answer: D