Since I am US, I am not sure about UK currency.
However, I can tell you how to set this up and you will have to be sure the currency works.
Let S = # student tickets and G = # of guest tickets
S + G = 290
S + 3G = 490
Subtract the 1st equation from the second to eliminate S.
Then solve for G and then use the value for G to get S.
Ahmed D.
Thank you very much .... I have been searching for a answer for a very long time and I wasn't able to find an answer ... You made it simple ... Thank you very much02/26/19