step by step 6r+7=13+7r
6r + 7 = 13 + 7r ....subtract 7r from both sides6r - 7r + 7 = 13 + 7r - 7r....simplify-r + 7 = 13....subtract 7 from both sides-r + 7 - 7 = 13 - 7...simplify-r = 6...multiply by -1 to make r positiver = -6
6r+7=13+7r6r-7r=13-7-r = 6r = -6