Regular price quantity is $42,500, Diana earns 6.75% of this, so she earns:
42,500 x 0.0675 = 2868.75
On sale price quantity is $22,000, Diana earns 4.3% of this, so she earns:
22,000 x 0.043 = 946
The total is 2868.75 + 946 = 3814.75
Answer is $3,814.75