Cho tam giác ABC. Gọi M, N lần lượt là trung điểm AB, AC, trên tia đối tia NM lấy điểm D sao cho N là trung điểm MD, cm: a, CD song song AM

b, CD = MB

c, tam giác BMC = tg DCM

d, MN ss BC

e, MN = 1/2 DC

Jackson earns $25 per hour as a tutor at the college library. he set a weekly spending budget of $130 each week and puts the remaining money in his savings account. how many hours must he work this week to have at least an extra $50 to put in his savings account