Answer: $10.70 would be Lin's Father final total
Explanation:
So the meal costs $20 so you have to multiply 20 * (0.50)=10
So subtract 10 from 20 and it equals 10
A sales tax is calculated buy doing 10 * 0.07= 0.7 (or 70 cents since we are dealing with money)
Add the 70 cents to his total after the coupon of $10 and it equals $10.70
so his total is $10.70
Hope this helps