Can anyone help me solve the following problem? Please include the formula:


A computer is on sale for $1600, which is a 20% discount off the regular price. What is the regular price?

It's all based on this:

X% of Y is Z

There are two ratios here: X% is X/100

The number after of is the denominator Z/Y

Thus X(%)/100 = (is)Z / (of)Y

Fill in the blanks. What do you get?

I do it by simple proportion.

100% is the regular price.
20% off is the discount
So, 80% is the sales price.

80% makes up $1600
1 % therefore makes up 1600/80 = $20
So, how much does 100% make up?

sale price=(1-%)first price
1600=(1-0.2)p
1600=0.8p
divide by 0.8 or multiply by 1.25
2000=2000
very simple