3= -50/6 + b

do you times 3/1 by 6 getting 18/6 in the end then do you add 50/6 getting 68/6????

Yes, you're right. Here's how I arrived at the same answer.

3= -50/6 + b

3 + 50/6 = b

3 + 8 1/3 = b

11 1/3 = b