Question

40 POINTS
Someone please answer question 7 only

Answer 1

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

Answer 2

• See below

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