College (Online)

Question

I am taking online classes and math has come up. I have had to do a lot of refreshing my memory and I have been able to do it on my own but when the below problems come up I have serious issues. Please help.

 

- Bob and Mary start traveling toward each other from 600 miles apart. Bob is traveling at 54 miles per hour; Mary at 55 miles per hour. Compute the time elapsed before they meet. Round your answer to one decimal place.

 

- Solve for the unknown value in the equation.
  9 + 4 = 4 + ?

 

- Solve for the unknown value in the equation.
  48 ÷÷ 4 = 2 ×× ?

 

- 

Answer 1

d = r · t

d_Bob = 54t

d_Mary = 55t

Sum of distances is 600

54t + 55t = 600

Now solve for t

 

9 + 4 = 4 + ?

9 + 4 = 4 + 9

 

48 ÷ 4 = 2 × ?

12 = 2 · ?

6 = ?

Answer 2

Hi Melanie from Martinsburg, WA. Hope you had a great day today. I can certainly understand getting back into the classroom. 

I am glad you contacted Wyzant. I am here to help. I will let you know, I will help you understand how to set up these kind of problems. It began with reading and understanding what the word problems gives you and wants you to find out. 

Here we go with the first problem:

So Mary and Bob are 600 miles apart. Traveling from their starting points and then meeting, they would have covered that 600 miles.

We also know, Mary has a certain speed[55 miles/hour] and Bob has a certain speed also has a certain speed[55 miles/hour]. From what the problem tells us, the distance traveled by both will equal 600 miles. WHAT we DON'T KNOW, is the time it takes for them to meet up with each other. We will label that UNKNOWN as  t for hours. This also implies, each traveled the same amount of time, but since one person's speed if slightly more that the other, that person will cover more distance that the other.

So, in setting up our equation if we all up the things we know with the things we don't know, we should get the total distance both cover. It looks like this: Speed is distance over time...miles per hours so

    600 miles  =   55mpht  +  54mpht     since t is in hours we can change

 

  600 miles = 55mpht + 54mpht     we rewrite this

 

  600 miles = 55mt + 54mt   Since these are like terms we combine them

 

  600 miles = 109mt   Remember m stands for miles, so to calculate for t 

 

     600 miles   =   109miles(t)          we divide both sides by 109 miles

     109 miles         109miles

                                                      do you know why we can cancel out

                                                      109 miles on the right? 

        600 miles    =   t                      now we can cancel out miles

        109 miles 

        600 ÷ 109  =  5.505 hours

  

Now put it into our original equation and substitute for t : will use 5.5

                    600 miles = 55mph(5.5) + 54mph(5.5) 

Do the calculation and see if it is correct...

 

The second problem...is an example of something in Algebra called the Reflexive Property which say at any number, let's say 'a' will equal 'a', so

                  a  =  a

With that said     a + b  =  b  + a, if a = a and b = b

So with your second problem the solution is 

             9 + 4 = 4 + ?       ? = 4

 

the third problem is confusing. Can you get back with me on that. I do not understand the problem. I am available to tutoring.

Contact me on Wyzant