b is decreased by 25% which means there will be (-ve) sign.
<h3>So,</h3>

- <em>Option 5 is correct!!~</em>
Standard form of given question :8.5016012×10^7
Hello!
You first have to find the total amount of apartments
35 + 55 = 90
There are 90 apartments
Then you find the percentage of them have a balcony
You do this by taking the amount of apartments that have a balcony over the total amount of apartments
35/90 = 0.39
0.39 as a percent is 39%
The answer is 39/100 or 39%
Hope this helps!