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40 POINTS
Someone please answer question 7 only

40 POINTS Someone Please Answer Question 7 Only class=

Sagot :

mhanifa

Answer:

  • See below

Step-by-step explanation:

Use distance formula:

  • d = st, where d- distance, s - speed, t - time

a)

Total distance is:

  • 8x + 10y = 70

Solve for x:

  • 8x = 70 - 10y
  • x = (70 - 10y)/8 = (35 - 5y) / 4

Solve for y:

  • 10y = 70 - 8x
  • y = (70 - 8x) / 10 = (35 - 4x) / 5

b)

Average speed is:

  • s(av) = d / t = 70 / (x + y)

c)

The second scenario:

  • 10x + 8y = 72

Combine with the first one and solve the system:

  • 8x + 10y = 70

Solve by elimination as below:

  • 5(10x + 8y) - 4(8x + 10y) = 5*72 - 4*70
  • 50x + 40y - 32x - 40y = 360 - 280
  • 18x = 80
  • x = 40/9

Find y:

  • 10*40/9 + 8y = 72
  • 8y = 72 - 400/9
  • 8y = 248/9
  • y = 31/9

Kayle130978
I know y is 31/9
Hope that helps a little
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