Answer:
The regular price=$750
Step-by-step explanation:
Step 1
Let the regular price be x
regular price=x
Step 2
The expression for the price after the discount is;
price after discount=regular price-discount rate×regular price
where;
regular price=x
discount rate=25%
replacing;
price after discount=x-(25/100)×x=x-0.25 x=0.75 x
price after discount=0.75 x
Step 3
Get the expression for the final bill as shown;
final bill=price after discount-gift certificate
where;
final bill=$522.50
price after discount=0.75 x
gift certificate=$40
replacing;
522.50=0.75 x-40
0.75 x=522.50+40
0.75 x=562.50
x=562.5/0.75
x=750
The regular price=$750
Answer:
Step-by-step explanation:
A calculator shows the value of 
meaning that each day, about 99.4% of the sample remains.
The formula 
Evaluate this at <em>t</em> = 16 to get 91 grams remain.
