妈妈买了3.5千克白菜，交给售货员2元。找回0.25元，每千克保持多少元。8D9O3o*k:}4w)z-X(e({
算式：提示(d,G2c8S5`9G.}0G;V+q(d/J8D9O3o*k:}4w)z-X(e({
答每千克保持1n7R0Y6I,}:w*g6n元。8D9O3o*k:}4w)z-X(e({