There were 100 pizzas sold at Brooklyn's pizzeria on Monday. A large pizza costs $16 and a small pizza costs $11. If $1550 worth of pizzas were sold in all, how many small pizzas were sold?

Let x be the number of small pizzas sold .....then 100 - x = the number of large pizzas sold

So

11x + 16 ( 100 - x) = 1550 simplify

11x + 1600 - 16x = 1550

11x - 16x = 1550 - 1600

-5x = -50

x = -50 / -5 = 10 small pzzas sold