The relative change from what Susan counts her class needs (old) to what Thomas counts his class needs (new) should be 26.32.
Since it required 24 sets of supplies for the week. Susan counts that her class only needs 19 supplies
So here the relative change be
= (24 - 19) / 19
= 0.263157 * 100
= 26.32
Hence, the relative change is 26.32.
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