<span>Solution
m = {-13, -1}</span>
Answer:
12% of 60, 400% of 18, 55% of 220
Step-by-step explanation:
12% of 60 =7.2
55% of 220 = 121
400% of 18 = 72
7.2, 72, 121
It opens upward and the vertex is (2,-6) here are some plotted points: (0,6),(1,-3),(2,-6),(3,-3),(4,6). Hope that helps. I hate graphing but if you do it enough times you'll get the hang of it!
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).
