The cost of his food, before the voucher, was $8 + $20 + $3 + $3 + $6 = $<<8+20+3+3+6=40>>40.
The tip was $40 * .20 = $<<40*.20=8>>8.
The voucher saved him $20 / 2 = $<<20/2=10>>10.
So the full price of Arthur's meal, with tip, was $40 - $10 + 8 = $<<40-10+8=38>>38.
#### 38