<u>Answer:</u>
29 years
<u>Step-by-step explanation:</u>
- Given the function
, where x stands for the number of years since the material was put into the vault, we can plug 140 into x to find the amount leftover. - Another way of doing this is to change the function to
which are equivalent functions, and then plug 140 into x. This function is helpful if you also needed to find the rate. - I'll use the 1st function because the question doesn't ask for the rate

From here I'll just use a calculator & get 28.7, or 29 years.
Answer:
Top left and bottom one
Step-by-step explanation:
If it adds to 90° then the answer is 49
and if it adds to 180° then the answer is 139
The graph is shown in the attached image.