Question

The cost of a ticket increases by 10% to £18.15. Work out the original cost ​

Answer 1

The original cost is £16.50

Explanation:

The best way to approach this question is by solving it algebraically. By constructing an equation that links the original cost to the current cost (let original cost be X), this would give you X*(1+10%) = £18.15. 10% is equal to 0.1. Therefore (1+10%) is actually 1.1. You can thus simplify the equation into 1.1*X = 18.15.To find X, you want to make X is the only subject. You can do so by dividing the equation on both sides by 1.1, making the equation X = 19.25÷1.1, which would give you X as 16.50. (The original price is 18.15).

Hope it helps.

Answer 2

Denote the original cost: x

The cost of a ticket increases by 10% to £18.15, then:

x*(1 + 10%) = 18.15

=> x*(1 + 10/100) = 18.15

=> x*(110/100) = 18.15

=> x = 18.15*(100/110) = 16.5£

Hope this helps!

:)