dancinggeometry wrote:

When X is divided by 7 the remainder is U, and when Y is divided by 7 the remainder is V. What is the value of U+V ?

(1) X+Y is divisible by 7

(2) X-Y is divisible by 7

X= 7k+U

Y= 7m+V

1)

X+Y = 7 (k+m)+U+V

which is divisible by 7

means U+V must be divisable 7 and also U<7 and V<7

so U+V=7

Sufficient

2)

X-Y = 7(k-m)+(U-V)

This is divisible by 7 when U-V is also divisible by 7

and also U<7 and V<7..

U-V must be zero. i.e U=V

U can be any number between 1 to 7

insuffcient

A

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