Carcass wrote:
Positive integer A > 10,000 and B > 20,000. When A is divided by 237, the remainder is 85. When B is divided by 237, the remainder is 41. What is the remainder when (2A + 3B) is divided by 237?
A. 0
B. 56
C. 123
D. 170
E. 211
Key property: We can take ANY possible values of A and B (that satisfy the given information) and use them to determine the remainder when (2A + 3B) is divided by 237.
So we can ignore the information that tells us A > 10,000 and B > 20,000, and just use the smallest possible values of A and B. Another property:
If N divided by D leaves remainder R, then the possible values of N are R, R+D, R+2D, R+3D,. . . etc. For example, if k divided by 5 leaves a remainder of 1, then the possible values of k are: 1, 1+5, 1+(2)(5), 1+(3)(5), 1+(4)(5), . . . etc.
Given: When A is divided by 237, the remainder is 85So,
85 is the smallest possible value of A.
Given: When B is divided by 237, the remainder is 41So,
41 is the smallest possible value of B.
Question: What is the remainder when (2A + 3B) is divided by 237?2A + 3B = 2(
85) + 3(
41) = 170 + 123 =
293293 divided by 237 equals 1 with remainder 56
Answer: B