Discover Questions

A relation ~ is defined on the set Z by the rule x~y if and only if x-y is a multiple of 4. Prove the relation ~ is reflexive and symmetric? Do cows like bulls? If the ratio of carbon-14 to carbon-12 in a piece of bone is only one-quarter of the atmospheric ratio, how old is the bone? Convertion of liter to cup? The line passing through point (4, -1) and perpendicular to the line whose equation is 2x - y - 7 = 0?