Question

I bought 10 presents for Christmas. Some were £20 and some were £22.50. If the total cost was £217.50 how many of the £22.50 presents did I buy​

Answer 1

Let's denote:

Number or gifts cost 20 = x

Number or gifts cost 22.5 = y

Then, we have:

x + y = 10

20x + 22.5y = 217.5

=> 20(10 - y) + 22.5y = 217.5

=> 2.5y = 17.5

=> y = 7 (Number or gifts cost 22.5)

=> x = 10 - 7 = 3 (Number or gifts cost 20)

Hope this helps!

:)