A commercial model lost 3 pounds after dieting for 15 days. At this rate, how many more days should the model continue dieting in order to lose a total of 20 pounds?

Question

Answer key shows 85. Show solution. Another question. What number must be divided by 9/4 to get 20%? Is the answer 0.45? And if it is 20% then why is the answer 0 and not 0.45? Another question. A certain number when raised by 130% gives 754. What is the number? Answer key shows x(130%) = 754, therefore x = 180. Others answered it as x + 130x100 = 754, therefore x = 327.83. Can you explain how you got the answer and why is the other answer is incorrect

Answer 1

1) Model loses 3 pounds every 15 days

So she loses 15/3 or 5 pound every day.

She has to lose 17 pounds more because she already has lost 3 pounds,

So total days required to lose 17 pounds = 17 *5 = 85

2) What number must be divided by 9/4 to get 20%?

Try to write it in equation

x*4/9  = x *0.2

but we know lhs is never equal rhs unless x = 0

3) Edit:

Edit: Your question said to raise x by 130% it doesn't say that 130% of x =754

But if you want 130% of x = 754

then,

130/100 * x = 754

=> x = 754*100/130 = 580