Danny had a sum of money. He spent $315 on a mobile phone and 3/5 of the remaining money on a headphone. He then had 1/10 of the sum of money left. How much money did Danny have at first?

Answer 1

Let's call the amount of money Danny had at first "x".

After he spent $315 on a mobile phone, he had x - 315 left.

He then spent 3/5 of that money on a headphone, which means he had 2/5 of it left. So:

2/5(x - 315) = 1/10x

Multiplying both sides by 10 to get rid of the fraction:

4(x - 315) = x

Expanding the brackets:

4x - 1260 = x

Subtracting x from both sides:

3x = 1260

Dividing by 3:

x = 420

So Danny had $420 at first.