8.64 - 3.15 = $5.49 if this is what you are asking
No, line graphs are used only to show change over time
In the balanced reaction
2 Fe + O₂ → 2 FeO
2 moles of iron (Fe) react with 1 mole of molecular oxygen (O₂) to produce 2 moles of iron oxide (FeO). The ratio of Fe to FeO is 1-to-1, so if one starts with 42.4 mol of Fe, one will end up with the same amount of FeO, 42.4 mol.
Look up the molar mass of Fe and O:
• Fe = 55.845 g/mol
• O = 15.999 g/mol
Then the molar mass of FeO is approximately 71.835 g/mol, and so the mass of 42.4 mol of FeO is
(42.4 mol) × (71.835 g/mol) ≈ 3050 g
So the trapezoid has 2 parallel sides making segments AD and BC transversals
Therefore making angle c and angle b add up to 180
(180-3x) + 3x + 180-9x +9x
180 +12x = 360
180= 12x
x= 15