Let x be the number of latter he sold this week
Let us first set the equation
y = 0.5x + 150 where y is the total pay
275 = 0.5x + 150
Let's go ahead and solve for x
substract 150 from both-side
275 - 150 = 0.50x
125 = 0.50x
Divide both-side by 0.50
250 =x
Hence, he sold 250 lattes
