A hardware store is offering 20 light bulbs at a total cost of $71.02, which includes a 6% sales tax. To prepare for a lab experiment, Brad is making a solution that uses two types of concentrations: 75 mL of 50% salt and 125 mL of 10% salt.

What is the salt concentration of the mixed solution?
Before taxes, how much did a single light bulb cost?

Mrs. julien’s and mrs. castillejo’s classes are selling cookie dough for a school fundraiser. customers can buy packages of macadamia nut chip cookie dough and packages of triple chocolate cookie dough. mrs. julien’s class sold 25 packages of macadamia nut chip cookie dough and 30 packages of triple chocolate cookie dough for a total of $221.25. mrs. castillejo’s class sold 5 packages of macadamia nut chip cookie dough and 45 packages of triple chocolate cookie dough for a total of $191.25. (a) write the system of equations that model the problem. be sure to explain which equation represents which situation. (b) find the cost of each type of cookie. show your work. (c) explain which method you used to solve the system and why you chose that method.