Iris Souza started the summer with $30. She took $10 and made signs for her dog walking service. She posted the signs all over her neighborhood. She used the other $20 to buy a stout leash and a pooper-scooper. At the end of the summer, after buying herself a new pair of shoes for $50 (she had worn her other shoes out walking dogs), she had $125 left. What was Souza’s profit for her summer job?