Start by naming the variables
x= basketballs
y=footballs
write the system of equations
also when he says up to means that the cost can be less or equal to 150
continue by graphing both of the equations
He could buy 6 basketballs and 2 footballs in order to spend $150
The black line represents the amount of balls Mr. Boyle needs, each point that lies on this line is a possible combination of how to buy the balls, the blue shaded region represents all the combinations that will cost less than $150, the point (6,2) is the maximim combination he can use.