If `A sube B and C sube D`, then prove that:
`A xx C sube B xx D`

Answer

N/a

Explanation

Let (x,y) in A xxC`
`implies x in A and y in C`
`implies x in B and y in D (because A subeB and C sube D)`
`implies (x,y) in BxxD`
`therefore A xx C sube BxxD` . Hence Proved.