Why do we not use FOIL when a bP t but do if its a bP tS

Why do we not use FOIL when a - b(P + t), but do if it\'s (a - b)(P + t)?

Solution

We use FOIL (First Outer Inner Last) for multiplying two binomials

In first equation a-b(P+t) it is subtraction of a ,b(P+t) according to BODMAS rule

In b(P+t) it is multiplication of uninary and binary expression .So FOIL is not used here

In case of (a-b)(P+t) it multiplication of two binary expressions .So FOIL is used