Question

He price of a computer was decreased by 20% to £136.
What was the price before the decrease?

Answer 1

The full price is represented by 100%. If this computer was decreased by 20%, so it worth 80% now.

So, we can make a rule of three: 80% value is equals to 136, how much is 100%?

80% ------------ 136

100% ----------- x

Let's multiply "making a x":

`80x = 136\cdot 100\\80x = 13.600\\x = (13600)/(80) \\x = 170`

Therefore, the price before the decrease was £170.

Answer 2

The original price is 170

Explanation:

Let x be the original price

x* .20 is the decrease

x - .20x = new price

.80x = new price

.8x = 136

Divide each side by .8

.8x/.8 = 136/.8

x =170