Erica has 70 shells that she collected. Susan has 70 times less than Erica. Bobby has 10 times more than Erica. How many shells do they all have together?

They have - 4060 Shells in total. Now this answer is odd because it is negative which means they have literally none. Without Susan they have 770 Shells in total. If you meant 10 times less than Erica it would be - 700 + 700 + 70 which would equal 70. I really don't think this equation is correct because of Susan's absurd amount of shells. If you could correct me with anything that i am doing wrong i am willing to take some criticism.