it is contrapositive
i could not see the question too well so check yourself again too . this is because i want you to get it correct.
so the possibilities of the measurement of the side of the triangle are either it is longest side or not the longest side
when it is the longest side
s < 25 + 35s < 60
if it is not the longest side
35 < 25 + s10 < sso 10 < s < 60so the perimeter70 < p < 130