Question

Check that 4 is a divisor of 28 - 20​

Answer 1

Since 4 is a divisor of 28 and 20, we will have to:

`\bold{28 = 4 * 7}`

`\bold{20 = 4 * 5}`

Subtracting member by member the previous equalities we will have:

`\bold{28 - 20 = 4*7 - 4*5}`

Taking out a common factor in the previous expression will result:

`\bold{28 - 20 = 4(7 - 5) = 4 * 2}`

That is to say, that 4 is a divisor of 28 - 20 since it is contained exactly 2 times in said difference.