Answer:
- <u>120 pens and 200 pencils.</u>
<u></u>
Explanation:
You can set a system of two equations.
<u>1. Variables</u>
<u />
- x: number of pens
- y: number of pencils
<u>2. Cost</u>
- <em>each pen costs</em> $1, then x pens costs: x
- <em>each pencil costs</em> $0.5, then y pencil costs: 0.5y
- Then, the total cost is: x + 0.5y
- The cost of the whole purchase was $ 220, then the first equation is:
x + 0.5y = 220 ↔ equation (1)
<u>3. </u><em><u>There were 80 more pencils than pens</u></em>
Then:
pencils = 80 + pens
↓ ↓
y = 80 + x ↔ equation (2)
<u>4. Solve the system</u>
i) Substitute the equation (2) into the equation (1):
ii) Solve
iii) Substitute x = 120 into the equation (2)
Solution: 120 pens and 200 pencils ← answer
Https://youtu.be/5C9LBF3b65s this should help you understand it
For this case we have the following equations:
2x - 3y = 1
2x + 3y = 2
When adding both equations we observe that:
Sentence 1: we have an equation of a variable, which in this case will be x. We can clear the value of x.
Sentence 2: Knowing the value of x, we can substitute in any equation and find the value of y.
Sentence 3: The value of x and y represents the point of intersection of both lines (x, y).
Answer:
y = 6
Step-by-step explanation:
If x varies inversely proportional as y.
, k is constant of proportionality
or
k = xy
When x = 3 and y = 10
k = 3×10
k = 30
Put x = 5,

So, the value of y is 6 when x is 5.
This is the graph of the equation