That would be 8. first parenthesis, then multiply, then subtract.
This is a units conversion problem: you have time and you want to convert that to money. Any units conversion problem involves multiplication by 1 in various forms. When you are given 7.5 min = 1 bottle = 500g, you know that (500 g)/(7.5 min) = 1 because the numerator and denominator are equal. (Of course, you are aware that 500 g = 0.500 kg.) The idea is to choose the forms of 1 that cause units you don't want to cancel, leaving only the units you do want.
![6\,h\times \dfrac{0.500\,kg}{7.5\,min}\times \dfrac{60\,min}{1\,h}\times \dfrac{5\,p}{1\,kg}\\\\=\dfrac{6\cdot 0.500\cdot 60\cdot 5\,p}{7.5\cdot 1\cdot 1}=120\,p](https://tex.z-dn.net/?f=6%5C%2Ch%5Ctimes%20%5Cdfrac%7B0.500%5C%2Ckg%7D%7B7.5%5C%2Cmin%7D%5Ctimes%20%5Cdfrac%7B60%5C%2Cmin%7D%7B1%5C%2Ch%7D%5Ctimes%20%5Cdfrac%7B5%5C%2Cp%7D%7B1%5C%2Ckg%7D%5C%5C%5C%5C%3D%5Cdfrac%7B6%5Ccdot%200.500%5Ccdot%2060%5Ccdot%205%5C%2Cp%7D%7B7.5%5Ccdot%201%5Ccdot%201%7D%3D120%5C%2Cp)
The glass for recycling that would save enough energy to power an oven for 6 hours costs 120p.
Answer: $56.50
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(instead of dividing each of them individually and them subtracting them one by one, combine them together as a fraction first and then subtract)
80 - (68/5 + 51/2 + 22/5)
= 80 - (136/10 + 255/10 + 44/10)
= 80 - (435/10)
= 80 - 43.5
= 56.5
He saved $56.50 on that
Answer: 5(x-1)
Step-by-step explanation: