Answer as many as possible please need work for brainilist

1. 18x + 35y = 598

  x + y = 20

  Isolate a variable in the second equation:

  y = -x + 20

  Plug y back into the first equation

  18x + 35(-x + 20) = 598

  18x - 35x + 700 = 598

  -17x +700 = 598

  -17x = -102

   x = 6

   You carpool 6 days of the 20

   6 + y = 20

   y = 14

   You ride the bus 14 days of the 20

2.   4.50n + 3p = 252

     p = 2n

     Substitute p into the first equation

     4.50n + 3(2n) = 252

     4.50n + 6n = 252

      10.5n = 252

      n = 24

      They sold 24 cans of nuts

      p = 2(24)

      p = 48

      They sold 48 boxes of popcorn

      The group sold, in total, 24 + 48 = 72 cans of nuts and boxes of popcorn.

3.  x - y = 3

    x + y = 8

    Isolate a variable

    x = y + 3

    (y + 3) + y = 8

    2y + 3 = 8

    2y = 5

    y = 2.5

    The average speed with wind is 2.5 mph

    x - 2.5 = 3

    x = 5.5

    The average speed without wind is 5.5mph

4. x + 8y = 22.8

   x + 6y = 18.6

   Isolate

   x = -8y + 22.8

   Substitute

   (-8y + 22.8) + 6y = 18.6

   -2y + 22.8 = 18.6

   -2y = -4.2

   y = -2.1

   The gas costs $2.10 per gallon

    x + 8(2.1) = 22.8

    x + 16.8 = 22.8

    x = 6

    The cost of the car was is $6.

5.  Cost = 9.99 + 2.49x

    Cost = 20.49 + 1.79x    

    To find which one is better, we need to set them equal to each other at first.

    9.99 + 2.49x = 20.49 + 1.79x

    9.99 + 0.70x = 20.49

    0.70x = 10.5

    x = 15

So, they cost the same at 15 rentals.

To find which one is the better deal let's see how much both cost after 16 rentals.

     Cost = 9.99 + 2.49(16)

              = 49.83

     Cost = 20.49 + 1.79(16)

              = 49.13

Therefore, Main Street is the better deal because after the equilibrium Main Street costs less than Big Video.

6.  x + y = 15

    .25x + .05y = 2.75

    Isolate

    x = -y + 15

    Solve

    .25(-y + 15) + .05y = 2.75

    -.25y + 3.75 + .05y = 2.75

    -0.2y + 3.75 = 2.75

    -0.2y = -1

    y = 5

    There are 5 nickels

     x + 5 = 15

     x = 10

     There are 10 quarters

7. x + y = 26

   x + .25y = 17

   Isolate

   x = -y + 26

   Substitute

   (-y + 26) + .25y = 17

   -0.75y + 26 = 17

   -0.75y = -9

   y = 12

   There are 12 quarters in his pocket

   x + 12 = 26

   x = 14

   There are 14 dollars

I hope this helps!!

- Kay :)

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step-by-step explanation:

i think the amount would be $140.62