1/2k -15 + 3/2k -5 how do i simplify this expression

Olivia uses the work below to determine 55% of 720 which explains the error in olivia’s solution

The local farm is advertising a special on fresh picked peaches. the farm charges $4.25 to pick your own peck of peaches and $3.50 for each additional peck you pick. write an equation for the total cost of peaches in terms of the number of pecks. deine your variables. how much does it cost to pick 3 pecks of peaches?

Liz had 140 pens and inna had 100 pens. after inna gave liz some pens, liz had 3 times as many pens as inna. how many pens did inna give liz?