Explanation:
these are multiplications.
you could also write
4 + 5×(p - 1)
now, we need to calculate the contents of brackets (if we can), then do the multiplications and divisions, before we can do the then remaining additions and subtractions.
if we cannot do a calculation directly (because there is a variable involved), we need to do and document the single steps for the individual parts involved.
so,
4 + 5×(p - 1) = 4 + 5×p + 5×-1 = 4 + 5p - 5 = 5p - 1
remember, a multiplication of 2 expressions is done by multiplying every term of one expression with every term of the other expression and adding the results up (by considering their individual signs, of course).