x = number of 1-cent stamps
y = number of 8-cent stamps
z = number of 12-cent stamps
We have 31 stamps all together, so x+y+z = 31.
"I have 4 more 1-cent stamps than 8-cent stamps" means we have the equation x = y+8. Whatever y is, add 8 to it to get x. Solve for y to get y = x-8.
You also have "twice as many one cent stamps as 12 cent stamps", so x = 2z. Solving for z gets you z = 0.5x
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x+y+z = 31
x+x-8+z = 31 ... y replaced with x-8
x+x-8+0.5x = 31 ... plug in z = 0.5x
2.5x-8 = 31
2.5x = 31+8
2.5x = 39
x = 39/2.5
x = 15.6
Your teacher made a typo somewhere because we should get a positive whole number result for x (since x is a count of how many 1-cent stamps we have).
Answer:
The distance from point A to given line is: 2√5 or 4.472 units
Step-by-step explanation:
Given equation of line is:

And the point is:

The standard form of equation of line is:

Converting the given equation into standard form

The distance of a point (x1,y1) from a line is given by the formula:

In the given details,
A = -1, B = 2, C = -14
x1 = -14, y1 = 5
Putting the values in the formula

Hence,
The distance from point A to given line is: 2√5 or 4.472 units
So 1=6/8 minute
1=3/4 minute
multiply both sides by 4
4=3 minutes
3 times what=15
divide by 3
what=5
4=3 minutes
mulitpliy both sides by 5
20=15 minutes
answer is 20 bags