The cost of 1 Sandwich is $7.50 and the cost of 1 side dish is $3.00. Theres a weekly sale (Buy 1 Sandwich and 1 side dish and get each additional at 1/2 price) Juan writes the expression to determine the total cost of 1 sandwich and n side dishes 10.50+1.50(n-1). He orders a Sandwich and the same number of side dishes each of the five days this week and all together pays $75 for these 5 lunches. Write an equation that can be used to find the number of side dishes juan ordered this week.