CPhill

OK......thanks, Alan  !!!!!

5      9      14

24    2      26

29   11     40

N (Algebra or Physics)   = N(Algebra) + N(Physics) - N(Algebra and Physics)   =

                                            29             +     14          -        5                    =

                                                   43     -    5    = 

                                                        38

15   40    55

55   10    65

70   50   120

Tablet and no smartphone   =  40

So    40 / 120   = 1/3    =  33 1/3 %

And you are correct    !!!!

I like the way you did this one, Rom....I have not seen this before.......very crafty !!!!

Part b is straightforward.......we would end up with a profit of 28*$20  = $560  for 28 days, if we bought the same items every day

However.....note that on every 5th day.......we would not actually have to buy any cups, because for the four previous days.....we would have purchased 5 extra cups each day

So....on those days, our daily expense would be $4 less because we would not have to buy any cups on these "5th days".....and this would happen 5 times in 28 days...this would reduce our monthly expenses by 5 * $4   = 20

So....assuming that we charged the same for every cup of coffee.....the totlal profit for 28 days  would be:

23 days * [ 51 - 31] + 5 days * [51 - 27 ] =  $580

There are infinite possibilities.....here's one

A = 2

B = -2

C = 6

So,  A + B + C  = 6

[20000 + 1000(2) + 300 + 10(-2) + 6]  = 22286

And 22286/ 22 =  1013

Well......if you have $50 to spend.. and you want to earn a $20 profit per day....then.........

Revenue - Expenses  = Profit   ......so.....

Revenue - $31   = $20      add 31 to both sides

Revenue  = $51

So....you need to earn $51......so each cup of coffee will be sold for :

51/20  = $2.55 per cup

Well....let's see.....for just one day for 20 people, you need:

20 cups, 40 cups of milk, 40 tsp coffee and 60 tsp sugar

The cups will cost $4......however....you'll be better off by buying the 25 cups for $4 [you get 5 more cups instead of buying two of the 10 cup packages at $2 each]

The 40 cups of milk will cost $2

The 40 tsp of coffee  will cost $14

And the 60 tsp of sugar will cost $3 for 10 tsp  + $8 for 50 tsp   = $11

So your minimum expenses for one day   =  $[ 4  + 2 + 14 + 11]   =  $31

Since you only have $30 to spend.....you'll either have to plan on serving fewer customers or you'll have to cut down on the sugar, milk and/or coffee  in each cup.....!!!!

4x+1=5+2(2x-4)

4x + 1  = 5 + 4x - 8     simplify

4x + 1 =  4x - 3     notice that this has no solution.......we can't add 1 to something and expect to get the same result by subtracting 3 from the same thing

Saladin, I answered this one here :  http://web2.0calc.com/questions/which-of-the-ordered-pairs-in-the-form-x-y-is-the-solution-equation