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Alex skateboards at a constant speed from his house to school 3.8 miles away. It takes him 18 minutes. What fraction represents

Paraphin [41]

Speed is expressed as the ratio of distance/time = d/t

in Alex's case, speed = (3.8 miles / 18 minutes)

. . . or simply

3.8/18

8 0

3 years ago

Evaluate this expression <br> (-7--9)*(8+2)

Marizza181 [45]

Before we get started, it is good to remember PEMDAS - the acronym that tells you the order to carry out equations.

P = parentheses
E = exponents
M = multiplication
D = division
A = addition
S = subtraction

Knowing this, we should start by doing the equations <em>within </em>each parentheses.

$(-7 - -9) *(8 + 2)$
$(2) *(10)$

So we did the addition and subtraction pieces within each group leaving us with the above equation. Now let's multiply:

$(2)*(10) = 20$

20 is the answer.

5 0

3 years ago

Please help! Thanks in advance.

alukav5142 [94]

In this problem, we need to plug in the given x values for $f(x)=0$ and find a and b.

When we plug in 1, we get: $2 \times {1}^{4} - 5 \times {1}^{3} - 14 \times {1}^{2} + a \times 1 + b = 0$

Simplify:
$2 - 5 - 14 + a + b = 0$
$- 17 + a + b = 0$
$a + b = 17$

We got our first statement about the values of the variables. If we find one more we can find those 2 variables.

We have another given root: 4.

Plug it in:
$2 \times {4}^{4} - 5 \times {4}^{3} - 14 \times {4}^{2} + a \times 4 + b = 0$
$512 - 320 - 224 + 4a + b = 0$
$- 32 + 4a + b = 0$
$4a + b = 32$

Now we have our second one. We can combine them:
$a + b = 17 \\ 4a + b = 32$

I use elimination method which is easier here.

Multiply the top equation by -1: $- a - b = - 17 \\ 4a + b = 32$

Add them up:
$3a = 15$

Simplify:
$a = 5$

Now we have a, we can plug in one of those equations to find b:
$5 + b = 17$
$b = 17 - 5$
$b = 12$

So, the answers are $a=5$ and $b=12$ .

6 0

3 years ago

Allison wants to ride her bicycle 60 miles this week. She has already ridden 12 miles. If she rides for 6 more days, what is the

anastassius [24]

Answer:

8 miles a day

Step-by-step explanation:

First you have to subtract the amount of miles she had already gone.

60 - 12 = 48

Next you have to divide by the remaining amount of days (6 days).

48/6 = 8

7 0

2 years ago

A mistake was made in mixing the lemonade—<br> PLEASE HELP!!

beks73 [17]

Answer:

Part A:

$4 + x = y$

$0.5*4 + 1*x = 0.7*y$

$x = 8/3\ quarts\ of\ 100\%\ solution$

$y = 20/3\ quarts\ of\ 70\%\ solution$

Part B:

$x + y = 10$

$2x + 3y = 23$

$x = 7$ and $y = 3$

Step-by-step explanation:

Part A:

The inicial concentration of the lemonade is 50%, and the volume is 4 quarts, and we will add x quarts of a lemonade with a concentration of 100%, so the total volume will be y, and the concentration will be 0.7, so we have that:

$4 + x = y$

$0.5*4 + 1*x = 0.7*y$

Using the value of y from the first equation in the second one, we have:

$2 + x = 0.7*(4 + x)$