急.急.请高人帮忙出300道二年级下学期进退位数学竖式题.

25 -15 -80 = 10 -80 = -70 26 -6 -64 = 20 -64 = -44 27 + 3 -48 = 30 -48 = -18 28 + 12 -32 = 40 -32 = 8 29 + 21 -16 = 50 -16 = 34 30 + 30 + 0 = 60 + 0 = 60 31 + 39 + 16 = 70 + 16 = 86 32 + 48 + 32 = 80 ...