Answer :
Answer:
She invested an amount of $3,000 in the first accont and $27,000 in the second account
Explanation:
Here, we want to get the amount invested in each of the accounts
To get this,let us write the simple interest formula
Mathematically, we have this as:
[tex]I\text{ = }\frac{PRT}{100}[/tex]Let the amount invested in the first account be $x, while that of the second account be $y
P represent the amounts invested
R is the rate of investment
T is the time (1 year)
The sum of these two is the $30000 she has to invest
Mathematically, we have this as:
[tex]x\text{ + y = 30000}[/tex]Let us get the interests on each of the accounts
For the first account, we have the interest as:
[tex]I_1\text{ = }\frac{x\times5\times1}{100}\text{ = }\frac{5x}{100}[/tex]For the second account, we have the interest as:
[tex]I_2\text{ = }\frac{y\times9\times1}{100}\text{ =}\frac{9y}{100}[/tex]The sum of these two is the interest value, which is as follows:
[tex]\begin{gathered} I_1+I_2\text{ = }\frac{5x}{100}+\frac{9y}{100}\text{ = 2580} \\ \\ 5x\text{ + 9y = 258000} \end{gathered}[/tex]So, we have two equations to solve simultaneously
The two equations are:
[tex]\begin{gathered} x\text{ + y = 30000} \\ 5x\text{ + 9y = 258000} \end{gathered}[/tex]We can solve this by substitution
Let us substitute for y
[tex]y\text{ = 30000-x}[/tex]Insert this into the second equation, we have this as:
[tex]\begin{gathered} 5x\text{ + 9(30000-x) = 258000} \\ 5x\text{ + 270000-9x = 258000} \\ 9x-5x\text{ = 270000-258000} \\ 4x\text{ = 12000} \\ x\text{ = }\frac{12000}{4} \\ x\text{ = 3,000} \end{gathered}[/tex]Recall:
[tex]y\text{ = 30000-x = 30000-3000 = 27000}[/tex]What this mean is that:
She invested an amount of $3,000 in the first accont and $27,000 in the second account