Let H and L is set of people suffered from heart ailment and lungs infections respectively.
n(H)=89
n(L)=98
n(H∩L)=K
maxn(H),n(L)≤n(H∪L)≤n(U)
Where, U is the universal set.
⇒98≤n(H∪L)≤100
⇒98≤n(H)+n(L)−n(H∩L)≤100
⇒98≤89+98−k≤100
⇒0≤89−k≤2
⇒−89≤−k≤−87
⇒87≤K≤89