Answer:
x=3
Step-by-step explanation:
15-7x=5x-21
12x=36
x=3
I think the Answer is 4d-6
Using a system of equations, it is found that David is 12 years old.
<h3>What is a system of equations?</h3>
A system of equations is when two or more variables are related, and equations are built to find the values of each variable.
The variables are given as follows:
- Variable z: Rebecca's age.
David is three times younger than the dad and twice as old as Rebecca, then:
Rebecca is 30 years younger than the dad, hence:
z = y - 30.
Then, since x = 2z and z = y - 30 and y = 3x, we solve for x to find David's age.
x = 2(y - 30)
x = 2(3x - 30)
x = 6x - 60
5x = 60
x = 60/5
x = 12.
David is 12 years old.
More can be learned about a system of equations at brainly.com/question/24342899
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Answer:
Step-by-step explanation:
A(-10,-3), B(7,14)
slope of AB = (-3-14)/(-10-7) = 1
slope of perpendicular to AB = -1
equation of perpendicular through C(5,12):
y-12 = -(x-5)
y-12 = -x+5
x = -y+17
x-intercept is the value of x when y=0.
x-intercept = 17
(0,17) is a point on CD.
Answer:
P = 12
Step-by-step explanation:
Given formula for the perimeter 'P' of a rectangle is,
P = 2L + 2W
If the values of L and W are,
L = 4 and W = 2
Perimeter of the rectangle = 2(L + W)
= 2(4 + 2)
= 2 × 6
= 12 units
Therefore, value of remaining variable 'Perimeter' = 12 units
(There is no use of 'pi' in calculating the perimeter of a rectangle).
