If Jemma sold 400 glasses frames at $5 each, she made 400*$5 = $<<400*5=2000>>2000
Jemma sold twice as many frames as Dorothy, meaning Dorothy sold 400/2 = 200 frames.
If Dorothy sold her glasses frames at half the price that Jemma sold hers, then it means she sold her glasses frames at $5/2 = $<<5/2=2.5>>2.5 per glasses frame.
In total, Dorothy made $2.5*200 = $<<2.5*200=500>>500 from the sale of her glasses frames.
Together, they made $2000+$500 = $<<2000+500=2500>>2500 from the sale of the glasses frames.
#### 2500