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Ilia_Sergeevich [38]
3 years ago
6

Derek is four times as old as sarah. two years ago the sum of their ages was 36. how old is each now?

Mathematics
1 answer:
Charra [1.4K]3 years ago
4 0
Let's write a system of equations. We will use D for Derek's age and S for Sarah's age:

D = 4S

(D - 2) + (S - 2) = 36

We can simplify the second equation:

D + S - 4 = 36

D + S = 40

Now we can use substitution to plug 4S in for D in the second equation:

(4S) + S = 40

5S = 40

S = 8

Sarah is 8 years old.
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Pls helpp
irina1246 [14]
  • you will need 2 busses to only transport the boys.
  • Mark is at (1 + 5/6) miles of his house.
<h3>How many buses would it take to carry only the boys?</h3>

We know that there are (3 + 1/2) groups, such that each group fill one bus.

2/5 of the students are boys, then the number of groups that we can make only with boys is:

(2/5)*(3 + 1/2) = 6/5 + 1/5 = 7/5 = 5/5 + 2/5 = 1 + 2/5

Then you can make one and a little less than a half of a group, which means that you need 1 and 2/5 of a buss to transport the boys, rounding that to the a whole number, you will need 2 busses to only transport the boys.

<h3>How far is Mark from his house?</h3>

The original distance is:

D = (2 + 3/4) miles.

But Mark only covers 2/3 of that distance, then we have:

d = (2/3)*D = (2/3)*(2 + 3/4) miles = (4/3 + 2/4) miles

d = (4/3 + 1/2) miles = (8/6 + 3/6) miles = (1 + 5/6) miles

Mark is at (1 + 5/6) miles of his house.

If you want to learn more about mixed numbers:

brainly.com/question/21610929

#SPJ1

7 0
1 year ago
PLEASE PLEASE HELP ME!
Paladinen [302]
The answer is D
alternate interior angles <span />
3 0
3 years ago
Read 2 more answers
Identify the center and radius from the equation of the circle given below. x^2+y^2+121-20y=-10x
Tcecarenko [31]

Answer:

Center: (-5,10)

Radius: 2

Step-by-step explanation:

The equation of the circle in center-radius form is:

(x-h)^2+(y-k)^2=r^2

Where the point (h,k)  is the center of the circle and "r" is the radius.

Subtract 121 from both sides of the equation:

x^2+y^2+121-20y-121=-10x-121\\x^2+y^2-20y=-10x-121

Add 10x to both sides:

x^2+y^2-20y+10x=-10x-121+10x\\x^2+y^2-20y+10x=-121

Make two groups for variable "x" and variable "y":

(x^2+10x)+(y^2-20y)=-121

Complete the square:

Add (\frac{10}{2})^2=5^2 inside the parentheses of "x".

Add  (\frac{20}{2})^2=10^2  inside the parentheses of "y".

Add 5^2 and 10^2 to the right side of the equation.

Then:

(x^2+10x+5^2)+(y^2-20y+10^2)=-121+5^2+10^2\\(x^2+10x+5^2)+(y^2-20y+10^2)=4

Rewriting, you get that the equation of the circle in center-radius form is:

 (x+5)^2+(y-10)^2=2^2

You can observe that the radius of the circle is:

r=2

And the center is:

(h,k)=(-5,10)

6 0
3 years ago
Read 2 more answers
Am I right or wrong plz help
ElenaW [278]

you are corret i hope

i helped

7 0
3 years ago
Helppp meee pleaseeee guysss?!!!??!?
RUDIKE [14]

Answer:

A. -1≤x≤6

Step-by-step explanation:

  • 6≥ x² - 5x
  • x² - 5x -6 ≤ 0
  • (x-6)(x+1) ≤ 0
  • x - 6 ≤ 0 ⇒ x ≤ 6
  • x + 1 ≥ 0 ⇒ x ≥ -1
  • -1 ≤ x ≤ 6

Choice A is the answer

7 0
2 years ago
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