1) find how many rocks Nellie counted by subtracting 156 from 336
336 - 156 = 180 rocks <- Nellie
2) find how many rocks Pat counted by adding 418 to 336
336 + 418 = 754 rocks <- Pat
3) find how many rocks Nellie and Pat counted by adding 180 and 754 together
180 + 754 = 934 rocks <- Nellie and Pat
4) your answer is 934 rocks, which is B
Hope this helped!
