Respuesta :

You will need to set up your table of values for each person.

Let x represent the months, and y for the amount of money.

For Carissa:                             For Louann:
x = y                                         x = y
--   --                                         --    --
0    $250                                 0   $1230
1    $330                                   1   $1170
2    $410                                  2   $1110
3    $490                                 3   $1050
4    $570                                 4    $990
5    $650                                 5    $930
6    $730                                 6    $870
7    $810                                 7    $810

You could also do the equation:
80x + 250 = -60x + 1250
where you will get x=7.
Then substitute 7 to the x's in the equation which will give you $810 for each.

The answer is: It will take 7 months. Then, they will both have $810 in their accounts.
AL2006

This exercise is trying to get you to write an equation
that describes what's going on.

Carissa has $250 today, and she adds $80 to it each month.
In  'm'  months from now, she'll have  80m  more than $250.

                C (for Carissa)  =  250 + 80m

Louann has $1230 today, and she takes out $60 each month.
In  'm'  months from now, she'll have  60m  less than $1230.

               L (for Louann)  =  1230 - 60m

Carissa has less money today, but it's growing $80 every month.
Louann has more money today, but it's losing $60 every month.
Eventually, they'll both have the same amount.
The question is:  When and how much ?

Well, when they both have the same amount, then  C = L .

                                         250 + 80m  =  1230 - 60m

That's the end of the hard part of this problem ... writing
the equation. The rest is easy, and I'm sure you'd have
no trouble solving it.  But since I'm on a roll, and I'm
going to take your 5 points, I might as well keep going:

                                           250 + 80m  =  1230 - 60m

Subtract 250 from each side:    80m  =    980 - 60m

Add  60m  to each side:            140m  =  980

Divide each side by  140 :                m  =  7

This is telling us that after 7 months, Carissa and Louann will both
have the same amount of money in their accounts.

The problem also asks us how much that is.  So let's find the
amount for both of them, just to check our work and make sure
they're both the same:

Carissa:   250 today + (7 months x $80/month) = 250+560 = $810 .

Louann:  1230 today - (7 months x $60/month) = 1230-420 = $810 

                                                                                                       yay !


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