3/2 is the rate of change
5b+4+10=-2
5b+14=-2
5b+14-14=-2-14 1) subtract 14 from both sides
5b=-16
5b/5=-16/5 2) divide by 5 on both sides
b=3 & 1/5
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).
Angles in a traingle always add up to 180°. in an isosceles triangle, 2 of the angles are the same, so if one angle is 100°, the other 2 must be 180-100=80/2=40
the other 2 angles would be 40° and 40°
