Answer:
80%
Step-by-step explanation:
Let's call the past exam mark m,
m*105%=84
m*105/100=84
m=84/(105/100)
m=80
Hope this helps!
1.742 x 10^-3
<em>This is because you have to move the decimal so there is no non zero digits left in the decimal point and if the number of decimal places you move will be the exponent on the "10". If you move the decimal to the right it will be a negative and if you move it to the left it will be a positive.
</em>
The price of fan was 20 Dollars 55 cents last week.
Step-by-step explanation:
Let,
The price last week = x
As the price is 27% lower than last week, therefore
(100%-27%) * Price last week = $15
73% * x = 15
Solving the percentage;

The price of fan was 20 Dollars 55 cents last week.
Keywords: Percentage, multiplication.
Learn more about percentages at:
#LearnwithBrainly
It could be 8 since 8x18= 144 and 144 divided by 2 is 72