<em>The length of a piece of ribbon glued around the edge of the lid is equal to the circumference of the lid. First, use the formula to find the approximate circumference of one jar lid.</em>
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<em>Next, since Bianca wants to glue ribbon around the edge of both jar lids, multiply this length by two.</em>
You can answer this because you know that 10 x 3 is 30, so if if the number of blocks tripled then the amount of time should triple as well because he's running at the same rate.