🔴 顺序反过来，结果差多少

一批金额 [120, 80, 200, 150]，门槛 100：留下不低于门槛的，各乘 10，再加起来。这正是 l1_basic_11 里用循环做过的那条流水线。把"过滤"和"乘 10"组合成流水线，两种顺序各跑一次：

A = [120, 80, 200, 150]
LINE = 100

def compose(f, g):
    """先做 g，再把结果交给 f"""
    return lambda x: f(g(x))

keep = lambda xs: [a for a in xs if a >= LINE]
x10  = lambda xs: [a * 10 for a in xs]

right = compose(x10, keep)     # 先过滤，再乘 10
wrong = compose(keep, x10)     # 先乘 10，再过滤
print(str(sum(right(A))) + "/" + str(sum(wrong(A))))