Cesar bought lunch at school. He had a sandwich and a drink that cost $12. His drink cost $3.50. Solve the equation 12=s+3.50 to find the cost of 's sandwich, s.

1. isolate the variable, in this case, d. subtract 35.5 on both sides of the equation.2. 52 subtracted by 35.5 is 16.53. therefore your answer would be d= 16.5this is the basics of pre algebra, isolating variable through adding, subtracting, multiplying, and dividing, if you have any other questions to ask just comment!