Answer:
Amount invested at 7% = 16000
Amount invested at 9% = 12000
Step-by-step explanation:
Let x be the amount invested at 7% and y be the amount invested at 9%.
Since the total amount invested is $28000, therefore, we can set up the first equation as:

Secondly, we are give that sum of two investments is $2200. Therefore, we can write the second equation as:

Now we need to solve these two equations to get the values of x and y.
First of all, we multiply the second equation with 100 in order to get rid of decimal values.

Let us use substitution method here. First of all we will solve for y from first equation and plug that into second equation.


Therefore, amount invested at 7% is $16000 and amount invested at 9% is 28000-16000=$12000.
Answer:
The food would last 51 days
Step-by-step explanation:
After 15 days are over, you could say that the 16th day would be as follows -
80 soldiers, food finished in 60 - 15 = 45 days.
If 20 more soldiers arrive, there would be a total of 100 soldiers, so if 80 soldiers can finish their food in 45 days - 1 soldier can finish = 45 * 80. Respectively, 100 soldiers can consume their food in ( 45 * 80 ) / 100 = 36 days.
As 15 days are already over, adding 36 more days = 51 days
The food would last 51 days if 20 <em>more</em> soldiers join after 15 days
<u><em>There are several possible ways to answer this question, but I hope that explanation helps!</em></u>
Answer:
E. 750 rounds to 800
Step-by-step explanation: first thing is to look at the tens value, numbers 1-4 get rounded down and numbers 5-9 get rounded up.
7u^3 - u^2 - 7 + 2u^3 - 4u^2
(7+2)u^3 -(1+4)u^2 - 7
9u^3 - 5u^2 - 7