The initial price of the sweater is $30. The store is having a sell that will reduce the price by 30%. This means that there is a reduction in the original amount of the sweater by 30% which is expressed as
30/100 × 30 = $9
The new price of the sweater would be 30 - 9 = $21
Since a sales tax of 5% will be added to the final purchase price, the value of the tax would be
It is a similar triangle so the side length of the smaller triangle (x and x-2) are in the same ratio as the bigger triangle (2x+5 and 2x-1). As the ratio is the same, you can equate them and solve for x.