Factorise fully $ac - ad - bd + bc.$ - Junior Cycle Mathematics - Question b - 2015

To factorise the expression $ac - ad - bd + bc$, we can rearrange it as follows:

$ac + bc - ad - bd$

Next, we group the terms:

$(ac + bc) + (-ad - bd)$

Now, factor out the common factors in each group:

$c(a + b) - d(a + b)$

Now, we can factor out the common factor $(a + b)$:

$(c - d)(a + b).$