Question

Loft insulation reduces annual heating costs by 20%.

Answer 1

Answer:

Without isolation annual cost would be 650$

Step-by-step explanation:

Without isolation annual cost is named x and it's worth 100%

With isolation annual cost is 520$ and it's worth (100%-20%) = 80%

Now we will make proportion

x : 520 = 100 : 80

When we multiply external and internal members we get

80 x = 100 · 520 => x = 100 · 520/80 = 650$

x = 650$

God with you!!!