First find the total number of purple beads Carly needs: 50 rows * 20 beads/row = <<50*20=1000>>1000 beads
Then find the total number of blue beads Carly needs: 40 rows * 18 beads/row = <<40*18=720>>720 beads
Then add the number of each color she needs to find the total number she needs: 1000 beads + 720 beads + 80 beads = <<1000+720+80=1800>>1800 beads
Then divide the number of beads by 10 to find the cost: 1800 beads / 10 beads/$1 = $<<1800/10=180>>180
#### 180