So for this, this can be written into the equation

(x = number of months, y = total cost).
To solve this problem, we need to plug in 1325 into the y-variable and solve from there.

Subtract 35 on each side to get

Then just divide by 50 on each side, and your answer should be

And because we cannot go past budget, we will have to round down to 25.
In context, the maximum amount of months Abbey can do is 25 months.
The equation for exponential decay is

, where <em>a</em> is the initial amount, <em>b</em> = 1 + <em>r</em> (the growth rate as a decimal number) and <em>x</em> is the number of time periods (in this case, minutes). Substituting the information we have:

. To the nearest tenth of a gram, this would be 1.0 grams.
He should invest $80,000 if he wants $8,000 at 10% interest. He can withdraw $8,000 at the end of each year. This is because if $8,000 is 10% of what he has in his bank account, to get the full amount (100%), we can multiply by 10, because 10% x 10= 100%. So $8,000 x 10= $80,000.