In the figure above，if the sum of each column，row，and five-element diagonal is equal to x，what is the value of p+r（）

单项选择题In the equation above，k，r，s，t，and v represent positive numbers． Multiplying which one of these numbers by 2 will reduce the value of n to of its present value（）

A. k
B. r
C. s
D. t
F. v

单项选择题If y is a two—digit number with tens digit t and units digit M and the table above is a multiplication table for t and u (for example，t×u=6)，then y2=（）

A. a+2b+10c
B. 10a+20b+x
C. 10(a+2b+c)
D. 100(a+26+c)
E. 100a+20b+c