1) We find out the value of B
The only possible values than can take B, would be the number 5, because 3x5=15; the other values don´t end at 5. (2x3=6; 2 x 8=16).
Therefore:
B=5
2)We find out the value of D.
We compute:
3 * 7+1=21 +1=22
22 end at 2, therefore:
D=2
3)We find out the value of A
We compute:
3 x A+2=10 x C + 4
3A+2=10C+4
3A=10C+4-2
3A=10C+2
If we multiply 3 x A, the result end at 2, the only one number multiplied by 3, it end at 2 is the number 4, the other numbers don´t end at 4 (3 x 6=18, 3 x 2=6...). Therefore :
A=4
We find out the value of C.
3 x 4 +2=12+2=14,
14 is a number that it start with the number "1" (tenth ), therefore:
C=1
Answer: A=4; B=5; C=1 and D=2.
