Let x be the cost of 1 pen
then cost of 1 notebook = x + 8.20
Let y be the number of pens Tan buys
then number of notebooks Tan buys = y/4
She spent $26 more on books than on pens which means
Cost of notebooks - Cost of pens = 26
(x + 8.20) * y/4 - xy = 26
Sinplifying it
(xy + 8.20y)/4 - xy = 26
(xy + 8.20y - 4xy)/4 = 26
8.20y - 3xy = 104
She spent $394 which means
Cost of notebooks + Cost of pens = 394
(x + 8.20) * y/4 + xy = 394
Simplifying it
(xy + 8.20y)/4 + xy = 394
(xy + 8.20y + 4xy)/4 = 394
8.20y + 5xy = 1576
Now, we have two equations,
(1) 8.20y - 3xy = 104
(2) 8.20y + 5xy = 1576
Now we need to find a third equation with either x or y as the subject of any of both the previous equations.
Let's make y the subject of (2) equation
8.20y + 5xy = 1576
y(8.20 + 5X) = 1576
(3) y = 1576/(8.20 + 5x)
Let's substitute the new value of y from (3) into (1) because we rearranged (2) to from (3)
8.20y - 3xy = 104
y(8.20 - 3x) = 104
y = 104/(8.20 - 3x)
1576/(8.20 + 5x) = 104/(8.20 - 3x)
1576 * (8.20 - 3x) = 104 * (8.20 + 5x)
12923.2 - 4728x = 852.8 + 520x
12923.2 - 852.8 = 4728x + 520x
12070.4 = 5248x
12070.4/5248 = x
x = 2.3
Now find the value of y by substituting the value of x in either equation, preferably (3)
y = 1576/(8.20 + 5x)
y = 1576/(8.20 + 5 * (2.3))
y = 80
Therefore cost of 1 notebook = x + 8.20 = 2.3 + 8.20 = $10.50
Answer:
3125 cm
Step-by-step explanation:
The distance between two villages is 0.625 km. Find the length in centimetres between the two villages on a map with a scale of 1:5000.
We are given the scale of
1: 5000
This means
1 km = 5000 cm
Hence:
1 km = 5000cm
0.625 km = x cm
Cross Multiply
x cm = 0.625 × 5000 cm
x cm = 3125 cm
Therefore, the length in centimetres between the two villages is 3125cm
Answer:
y + 4 = ⅕(x + 7)
Step-by-step explanation:
The "point-slope" form of the equation of a straight line is:
y − y₁ = m(x − x₁)
where m is the slope and (x₁, y₁) is a point on the line.
If m = ⅕ and (x₁, y₁) = (-7, - 4), the point-slope equation is
y + 4 = ⅕(x + 7)
The Figure below shows the graph of your line and a point at (-7, -4).
