Answer:
Here, length is 8 in. Width is 4in. and height is (3+3+3)=9 in. Then use the formula.
A= 2wl+2hl+2hw
= 2×4×8 + 2×9×8+2×9×4
=280 inch²
Answer : The substances half life in days is, 5.6 days.
Step-by-step explanation :
Half life : It is defined as the amount of time taken by a radioactive material to decay to half of its original value.
All radioactive decays follow first order kinetics.
The relation between the half-life and rate constant is:

where,
k = rate constant = 0.1235 per days
= half-life
Now put all the given values in the above formula, we get:


Thus, the substances half life in days is, 5.6 days.
Ok but what did i do wrong and if you never studied the subject how did you know i was wrong
Answer:
Justin travels 211.83 miles on 8.2 gallons of gas.
Step-by-step explanation:
77.5 miles / 3.1 gallons = x miles / 8.2 gallons
Solve for x... multiply by 8.2 gallons on both sides (that cancels it on the right) side of the equation.
8.2 gallons *77.5 miles / 3.1 gallons = x
635.5/ 3.1 = x
211.83 miles = x