Answer-
Equation for this situation,

Solution-
The total amount of money that Robert has = $50
Price of each slice of pizza = $5
Price of each game = $
= $2.5
Let x = number of pizza he can buy, and y = number of game he can play
So,





Plotting the graph we get the intercepts as,
x- intercepts = 10
y- intercepts = 20
x- intercepts is the point where, y=0, so in this case if does not play any game he can buy 10 slices of pizza.
y- intercepts is the point where, x=0, so in this case if he does not eat any pizza he can play 20 games.