zoom612 wrote:

When positive integer n is divided by 3, the remainder is 2; and when positive integer t is divided by 5, the remainder is 3. What is the remainder when the product nt is divided by 15?

1) n-2 is divisible by 5

2) t is divisible by 3

C must be it!

Given

n = 3k+2 and t=5l+3

S1. n-2 = 5m => n = 5m+2

Thus, n = 15q+2 insufficient.

S2. t = 3m

Thus, t= 15Q+3 insufficient.

Combine S1 and S2

nt = (15q+2)(15Q+3)

remainder is 2*3 = 6

sufficient

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