Ok, I'll help!
a) 35s+20p=150
b) Because she buys 3 sweaters, her total for sweaters is 35*3=105. [My] equation now is 105+20p=150, where 20p is the total money Holly spends on the sweaters. Subtract 150 from both sides, so 20p=45, and p=2.25. But she can't buy 2.25 pants, so this is the total whole number of pants she can buy without going over her money limit. Therefore it is 2, because the quotient when 45 is divided by 20 is 2.
c) Again, [my] equation is when p=0 35s=150. Holly can buy 1 sweater safely without going over the limit, 2 sweaters, 3, and 4. But when[ I ]reach 5, she can't, as she will spend 15*5=$175 on her sweaters, which is OVER her limit. So the greatest number of sweaters she can buy when she buys no pants is 4.