Answer:
y = -27
Step-by-step explanation:
y = kx
-15 = k5
-3 = k
The constant in the equation is -3.
y = -3x
y = -3(9)
y = -27
Answer:
$13,000 at 7% and $12,000 at 4%
Step-by-step explanation:
Use formula:
![I=P\cdot r\cdot t,](https://tex.z-dn.net/?f=I%3DP%5Ccdot%20r%5Ccdot%20t%2C)
where
I = interest,
P = principal,
r = rate (as decimal),
t = time (in years)
<u>7% rate:</u>
P = $x
r = 0.07
t = 1 year
Then
![I_1=x\cdot 0.07\cdot 1\\ \\I_1=0.07x](https://tex.z-dn.net/?f=I_1%3Dx%5Ccdot%200.07%5Ccdot%201%5C%5C%20%5C%5CI_1%3D0.07x)
<u>4% rate:</u>
P = $(25,000 - x)
r = 0.04
t = 1 year
Then
![I_2=(25,000-x)\cdot 0.04\cdot 1\\ \\I_2=0.04(25,000-x)](https://tex.z-dn.net/?f=I_2%3D%2825%2C000-x%29%5Ccdot%200.04%5Ccdot%201%5C%5C%20%5C%5CI_2%3D0.04%2825%2C000-x%29)
If he receives an annual return of $1,390, then
![I_1+I_2=1,390,](https://tex.z-dn.net/?f=I_1%2BI_2%3D1%2C390%2C)
so
![0.07x+0.04(25,000-x)=1,390\\ \\7x+4(25,000-x)=139,000\\ \\7x+100,000-4x=139,000\\ \\7x-4x=139,000-100,000\\ \\3x=39,000\\ \\x=13,000\\ \\25,000-x=25,000-13,000=12,000](https://tex.z-dn.net/?f=0.07x%2B0.04%2825%2C000-x%29%3D1%2C390%5C%5C%20%5C%5C7x%2B4%2825%2C000-x%29%3D139%2C000%5C%5C%20%5C%5C7x%2B100%2C000-4x%3D139%2C000%5C%5C%20%5C%5C7x-4x%3D139%2C000-100%2C000%5C%5C%20%5C%5C3x%3D39%2C000%5C%5C%20%5C%5Cx%3D13%2C000%5C%5C%20%5C%5C25%2C000-x%3D25%2C000-13%2C000%3D12%2C000)
The answer is 10x because two negatives make a positive so instead of subtracting, you add 7x+3x which is 10x