X = pencils, y = pens
8x + 6y = 8.50
4x + 4y = 5.....multiply by -2
----------------
8x + 6y = 8.50
-8x - 8y = -10 (result of multiplying by -2)
-----------------add
-2y = - 1.50
y = -1.50 / -2
y = 0.75 <=== pens cost 0.75
4x + 4y = 5
4x + 4(0.75) = 5
4x + 3 = 5
4x = 5 - 3
4x = 2
x = 2/4
x = 0.50 <== pencils cost 0.50
21
is what I got on my calculator
C=8πab
Divide both sides by 8πb
c/(8πb) = a
Answer:
the equation is
y = 0.75x
And, the constant of proportionality is 0.75
Step-by-step explanation:
The computation is shown below:
Given that
4y = 3x
And,
12y = 9x
Here the equation that represent proportional relationship is
4y = 3x
Divide both sides by 4
y = 3x ÷ 4
Now
12y = 9x
divides both sides by 12
y = 9 ÷ 12x
y = 3 ÷ 4x
y = 0.75x
so the equation is
y = 0.75x
And, the constant of proportionality is 0.75