Budgeting

Kamal Co has produced the following performance analysis for the January to March quarter during which no changes were made to the specification of its product.

Number of units:Budget $6,000, Actual $7200

$
Revenue 540,000 633,600
Labour (48,000) (58,716)
Materials (210,000) (205,000)
FO (69,000) (79,500)
Profit 213,000 290,384

As a result of the results in January to March, Kamal Co reconsidered its approach to budgeting and adopted a form of rolling budgeting, starting in April for the next twelve months. The budgeted figures for the remainder of the year before the rolling budget was introduced were as follows:
$
April-June 550,000
July-September 560,000
October-December 575,000
Kamal Co amended the budget so that budgeted sales for April-June were 20% higher than in the original budget, and then increased by 5% in July-September and October-December. It did not subsequently amend the budget for July-September. Actual sales for July-September were
$610,000.
Calculate the difference in the total sales operational variance, using the original budgeted and revised (rolling) budgeting figures.

1. The answer is $133,000
2. How to obtain the answer? ( the working is a bit confusing to understand?