Logarhythm

48 hours ÷ 3 days = 16 hours a day. 

If a gardener works for 8 hours a day, 2 gardeners are needed each day. 

The project is 3 days long so 2 x 3 = 6 gardeners, which is your answer :)

(x + 2)(3x² - x + 5)

= 3x³ - x² + 5x + 6x² - 2x + 10

= 3x³ + 5x² + 3x + 10

A = 3

B = 5

C = 3

D = 10

A + B + C + D = 3 + 5 + 3 + 10 = 21, which is your answer :)

Horse 24 feet from center: 

     r = 24ft

     circumference = (24 * 2)π 

                             = 48π

     48π * 32 = 1536π (which is the distance that horse travelled)

Horse 8 feet from center:
 
      r = 8ft

      circumference = (8 * 2)π

                              = 16π

      1536π ÷ 16π = 96 revolutions, which is your answer :)

Faster way would be to just multiply 32 revolutions by 3 since 24 ÷ 8 = 3 so the number of revolutions would have to be tripled

3/4 are black. 

1/4 * 4/7 = 1/7 are blue

1 - (3/4 + 1/7) = 1 - (25/28) = 3/28 are silver. 

3/28 = 9
 

1/28 = 3

3 x 28 = 84, which is your answer :)

4 = 2² and 8 = 2³

4¹⁰ = (2²)¹⁰ = 2²⁰

8²⁰ = (2³)²⁰ = 2⁶⁰

2²⁰ x 2⁶⁰ = 2^{(20 + 60)} = 2⁸⁰, which is your answer :)

3(3x⁷ + 8x⁴ - 7) + 7(x⁵ - 7x² + 5)

= 9x⁷ + 24x⁴ - 21 + 7x⁵ - 49x² + 35

= 9x⁷ + 7x⁵ + 24x⁴ - 49x² + 14

The sum of the coefficients = 9 + 7 + 24 - 49 = -9, which is your answer :)

For simplicity sake, let's call Train A "A" and Train B "B". 

A + B = 192

A > B

A - B = 120

192 ÷ 2 = 96

96 ± 120 ÷ 2 = 96 ± 60 = 156, 36

Train A weighs 156 tons and Train B weighs 36 tons :)

1) 8/10 of the slips have a 3 on them while 2/10 of the slips have an 8 on them. This means it's most likely that the number 3 will be drawn. 

2) Now there are 8/11 slips that have a 3 on them while there are 3/11 slips that have an 8 on them. This still means that the number 3 will most likely be drawn. 

The wording is kind of weird... I'm going to assume you mean "what is the expected number on the marble when one is selected from the bag"

There are 10 marbles. 8/10 have the number '5' on them and 2/10 have the number '3' on them. This means it's most likely that the number on the marble is 5 when drawn from the bag.