Sophie is 3.5 years younger than her brother. She knows that when she is b years old, her brother is b+3.5 years old. Right now, Sophie is 11.5 years old. How old is Sophie's brother?
Write your answer as a whole number or decimal.

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!