Would appreciate if anyone could show me how to do the following :-

Euan plays in a snooker tournament which consists of 20 games

He loses x games and wins y games

a) Write down an equation in x and y to illustrate this information.

b) He is paid £5 for each game he wins and £2 for each game he loses.

He is paid a total of £79

Write down another equation in x and y to illustarte this information.

c) How many games did Euan win.

I am happy with a) x+y=20 and b) 5x+2y=70 but

would like to know how to work out step by step c) above