Out of the 500 marbles that Cindy had, she gave her four friends 80 marbles each. What's four times the number of marbles she has remaining?
Cindy gave her four friends 80 marbles each, a total of 4*80 = <<80*4=320>>320 marbles
She was left with 500-320 = <<500-320=180>>180 marbles
Four times the number of marbles she has remaining is 180*4 = <<180*4=720>>720
#### 720