To answer the problem, let x be the number of apples Maria picked. By this representation, the number of apples Andre picked is 3x and that Jane picked 6x apples. The sum of all apples picked is 840. The equation that represent the situation is,
x + 3x + 6x = 840 ; x = 84
Andre picked 3x apples. Thus, Andre picked 252 apples.
The constant of proportionality is the ratio between two directly proportional quantities. Two quantities are directly proportional when they increase and decrease at the same rate.