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Alex777 [14]
3 years ago
10

A family has two cars. The first car has a fuel efficiency of 15 miles per gallon of gas and the second has a fuel efficiency of

25 miles per gallon of gas. During one particular week, the two cars went a combined total of 975 miles, for a total gas consumption of 55 gallons. How many gallons were consumed by each of the two cars that week?
Mathematics
1 answer:
Lera25 [3.4K]3 years ago
6 0
15x+25y=975
x+y=55

Rearrange equation two so x is by itself.
x=-y+55

Plug the rearranged equation two into equation one.
15(-y+55)+25y=975

Evaluate the 'new' equation 1.
-15y+825+25y=975
10y+825=975
10y=150
y=15

Choose an equation to evaluate with y to get x. (i chose equation 2 because it was easier)
x+15=55

Evaluate the equation
x=55-15
x=40

So now we have x=40 and y=15

Evaluate those two terms with both equations to check the correctness.
15(40)+25(15)=975
600+375=975
975=975 (correct)

40+15=55
55=55 (correct)

Both equations are correct so the values of x and y are true.
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What is 2x + 4x + 4 = 4(x + 4) and step by step and Highlight / circle the error
mario62 [17]

Answer:

x = 6 and the +4x is wrong

Step-by-step explanation:

2x + 4x + 4 = 4(x + 4)

6x + 4 = 4x + 16

+4x +4x  <--( <u>This part is wrong</u> )

10x + 4 = 16

-4 -4

10x = 12

10 10

x = 1.2

Correct steps

2x + 4x + 4 = 4(x + 4)

6x + 4 = 4x + 16

-4x        -4x

2x + 4  = 16

      -4     -4

2x = 12

2       2

x = 6

6 0
3 years ago
Two fractions are given. For each one, write its decimal equivalent and determine if the decimal is terminating or non terminati
ziro4ka [17]

Answer:

9/20 yes, 4/15 not. See below

Step-by-step explanation:

Pick 9/20 and multiply numerator and denominator by 5:

9/20 = 45/100

We know that if we divide a number by 100 we need to move the coma as two places left, so:

9/20 = 45/100 = 0.45

And this is a terminal decimal as we know where it ends.

On the other hand if we pick 4/15 let try to divide it (here I will do it 'manually'):

4 |_ 15

we can divide 4 by 15, so we use 40 and begin with a comma

40 |_ 15

      0.

15 enters 2 times in 40 with a rest of 10, so:

40 |_ 15

  30  0.2

  100

100 divided by 15 is 6 and we have 10 as rest again, and again and again...

40 |_ 15

  30  0.266.....

  100

    100

      ....

So, we will have 0.266666666666666 infinitely. The decimal for 4/15 is non terminating and is 0.26666666666666666...

6 0
3 years ago
Is the function y=10 linear or nonlinear?
Alja [10]
Nonlinear because its not changing in y values
4 0
3 years ago
If x and y are two nonnegative numbers and the sum of twice the first ( x ) and three times the second ( y ) is 60, find x so th
Dennis_Churaev [7]
If we translate the word problems to mathematical equation,
 
                             2x + 3y = 60

The second equation is,
 
                            P = xy³

From the first equation, we get the value of y in terms of x.
  
                             y = (60 - 2x) / 3

Then, substitute the expression of y to the second equation,
 
                            P = x (60-2x) / 3
                            P = (60x - 2x²) / 3 = 20x - 2x²/3

We derive the equation and equate the derivative to zero.

                           dP/dx = 0 = 20 - 4x/3

The value of x from the equation is 15.

Hence, the value of x for the value of the second expression to be maximum is equal to 15. 
                               
4 0
4 years ago
12x-y when x= 1/3, y=-2
Basile [38]

Answer:

Step-by-step explanation:

12 x 1/3-2

4 0
3 years ago
Read 2 more answers
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