问题详情

In the standard (x,y) coordinate plane, point M with coordinates (5,4) is the midpoint of AB, and B has coordinates (7,3). What are the coordinates of A ？
A.(17,11)
B.(9, 2)
C.(6, 3.5)
D.(3, 5)
E.(3, 5)请帮忙给出正确答案和分析，谢谢！