Answer:
Maria picked 84 lbs of apples
Explanation:
Let's denote Maria as x
Andre picks 3 times as many as Maria, 3x
Jane picks 2 times as many as apples as Andre, 2(3x), or 6x
The total weight of all the apples picked was 840 lbs, so
840 = x + 3x + 6x combine like terms
840 = 10x divide both sides by 10
84 = x
Therefore, Maria picked 84 lbs of apples