N - Nicholes money
M - Marys money
(1) N + M = 4800 ⇒ N = 4800 - M
(2) N - 800 = M - 2/5M ⇒ N - 800 = 3/5M
subtitute (1) to (2)
4800 - M - 800 = 3/5M
4000 - M = 3/5M
-M - 3/5M = -4000
-8/5M = -4000 |multiply both sides by (-5/8)
M = 2500
subtitute the value of M to (1)
N = 4800 - 2500
N = 2300
Answer: Mary had at first $2500. (Nichole: $2300).
Answer:
k = 11.
Step-by-step explanation:
y = x^2 - 5x + k
dy/dx = 2x - 5 = the slope of the tangent to the curve
The slope of the normal = -1/(2x - 5)
The line 3y + x =25 is normal to the curve so finding its slope:
3y = 25 - x
y = -1/3 x + 25/3 <------- Slope is -1/3
So at the point of intersection with the curve, if the line is normal to the curve:
-1/3 = -1 / (2x - 5)
2x - 5 = 3 giving x = 4.
Substituting for x in y = x^2 - 5x + k:
When x = 4, y = (4)^2 - 5*4 + k
y = 16 - 20 + k
so y = k - 4.
From the equation y = -1/3 x + 25/3, at x = 4
y = (-1/3)*4 + 25/3 = 21/3 = 7.
So y = k - 4 = 7
k = 7 + 4 = 11.
Let x - hours Carlos drove ; Let y - hours Maria drove
Equation 1: x + y = 4.4
x = 4.4 - y
Equation 2: 55x + 50y = 233
55(4.4 - y) + 50y = 233
242 - 55y + 50y = 233
-5y = 233-242
-5y = -9
y=9/5 or 1.8 hours Maria drove
To find time Carlos drove:
x=4.4 - 1.8
x = 2.6 hours
Answer:
$120.14
Step-by-step explanation:
This question is an example of a compound percentage decrease.
To work this out you would first need to convert the percentage of 25 into a decimal. You can do this by dividing the percentage of 25 by 100, this gives you 0.25. This is because percentages are out of 100.
The next step is to minus 0.25 from 1, this gives you 0.75. This is because we are working out the percentage decrease.
The final step is to multiply the amount of 900 by 0.75 to the power of 7, this gives you $120.14.
1) Divide 25 by 100.
2) Minus 0.25 from 1.
3) Multiply 900 by 0.75 to the power of 7.
