James had more paper clips than Andy. Mary had 70 paper clips. If three of them had 520 paper clips altogether, express Mary's paper clips as a percent of Andy's paper clips?

%

Set Andy's paper clips as 4 units and James paper clips as (4 + 1) units. Then,

4 units + 5 units = 520 – 70 = 450

9 units = 450

1 unit = 450 ÷ 9 = 50

Andy's paper clips = 4 units = 4 × 50 = 200

Thus, 70 ÷ 200 = 0.35 = 35%