3. In the calculations shown, each letter stands for a digit. They are used to make some two-digit numbers. The two numbers on the left have a total of 79 .
What is the total of the four numbers on the right?
A 79
B 158
C 869
D 1418
E 7979
SOLUTION
B

The numbers on the left use the digits $\mathrm{M}$ and $\mathrm{K}$ in the Units column, and the digits $\mathrm{J}$ and $\mathrm{L}$ in the Tens column. The numbers on the right use the digits $\mathrm{M}$ and $\mathrm{K}$ twice in the Units columns, and the digits $\mathrm{J}$ and $\mathrm{L}$ twice in the Tens column, so the total is exactly twice that of the numbers on the left. Twice 79 is 158 , answer B.