9x - y = 15
2x + 8y = 28

Use the substitution method.
Solve for y in the first equation.

9x - y = 15
-y = 15 - 9x
y = -15 + 9x

Now plug in y into the second equation.
2x + 8(-15 + 9x) = 28
2x - 120 + 72x = 28
74x - 120 = 28
74x = 148
x = 2

Plug x back into the rewritten first equation.
y = -15 + 9(2)
y = -15 + 18
y = 3

x = 2, y = 3

5 0

2 years ago

Robert makes 50 litres of green paint by mixing litres of yellow paint and litres of blue paint in the ratio 2:3.

podryga [215]

Answer:

Explanation:

1. Cost of each liter of yellow paint:

Yellow paint is sold in 5 litre tins and ach tin costs £26, thus the cost of one liter is £26 / 5 liters = £5.2 per liter.

2. Cost of each liter of blue paint:

Blue paint is sold in 10 litre tins and each tin costs £48, thus the cost of one liter of blue paint is £48 / 10 liters = £4.8 per liter

3. Cost of each liter of green paint.

Green paint is made by mixing yellow paint and blue paint in the ratio 2:3

Thus, 5 liters of green paint will cost:

2 liters yellow paint: 2 liter × £5.2 / liter = £10.4

3 liters blue paint: 3 liter × £4.8 / liter = £14.4

========== ========

5 liters green paint: 5 liter £24.8

Cost of one liter of gree paint: £24.8 / 5 liter = £4.96 / liter

4. Profit

Price of each liter of green paint: £66.96 / 10 liters = £6.696 / liter = £6.70 / liter

Profit per liter = price per liter - cost per liter = £6.70/liter - £4.96 / liter = £1.74 / liter

Percentage profit = profit per liter / cost per liter × 100

Percentage profit = (£1.74 / liter) / (£4.96/liter) × 100 = 35.08% = 35%

4 0

3 years ago

A wheel with radius 1 foot makes 1 revolution in 4 seconds. What is the linear velocity, in feet per second, of a point on the e

3241004551 [841]

Radius = r = 1 foot

Angular velocity = w = 1 revolutions in 4 seconds

So,

w = 0.25 revolutions per second

Since,

1 revolution = 2π radians

We can write the above equation as:

w = 0.25 x 2π radians per second = 0.5π radians per second

Linear Velocity = v = r w

Using the values, we can write:

v = 1 x 0.5π

= 0.5 π

= π/2 feet per second

Therefore, the correct answer is option B

7 0

2 years ago

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