Presented Below Are the Income Statements for Saldron Manufacturing for the Years

Presented below are the income statements for Saldron Manufacturing for the years ended December 31, 20X3, 20X2, and 20X1
$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\text { Saldron Manufacturing }$
$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\text { Comparative Income Statements }$
$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\text { For years ending December } 31$

$\begin{array}{l}\begin{array}{lll}\\ \text { Sales}\\ \text { Less: Cost of Goods Sold:}\\ \text { Beginning Inventory}\\ \text { Purchases}\\ \text { Cost of Goods Available for Sale}\\ \text { Less: Ending Inventory}\\ \text { Cost of Goods Sold}\\ \text { Gross Profit}\\ \text { Less: Operating Expenses}\\ \text { Income Before Taxes}\\ \text { Income Tax Expense (40 \%) }\\ \text { Net Income}\\\end{array}\begin{array}{lll}\underline{20 \times 3}\\{\$ 910} \\\\90 \\\underline{550} \\640 \\\underline{80} \\\underline{560} \\350 \\\underline{70} \\280\\\underline{112} \\\underline{\$ 168}\end{array}\begin{array}{lll}\underline{20 \times 2}\\{\$ 790} \\\\70 \\\underline{510}\\{580} \\\underline{90} \\\underline{490} \\300 \\\underline{60} \\240 \\\underline{96} \\\underline{\$ 144}\end{array}\begin{array}{lll}\underline{20 \times 1}\\{\$ 620} \\\\60 \\\underline{420} \\480 \\\underline{70} \\\underline{410} \\\underline{210} \\50\\160 \\\underline{64} \\\underline{\underline{\$96}}\end{array}\end{array}$

In 20X4 it was discovered that the 20X1 ending inventory was understated by $20, and the 20X3 ending inventory was overstated by $10. The 20X1 beginning inventory and the 20X2 ending inventory were correctly stated.
Identify the accounts which are incorrect on the 20X1, 20X2, and 20X3 income statements. State the dollar error (by how much they are incorrect) and whether the amounts overstate or understate balances.