When you unfold the paper, notice that there are two shaded areas. So 12 units = 2 unshaded areas 54.

Since you know that figure 2 is 7 units and 7 units = 1 unshaded area and 54, find the difference (in terms of units) between figure 1 and figure 2.

Then, you will realise that the unshaded area is 5 units. Hence, 54 = 2 units, find value of 1 unit and multiply by 12 to find area of paper.

Hope this helps:))