2x+5y=99 When y=−19,x=97; since x≥y; the maximum value of y is 13 and corresponding value of x is 17 We know that the solutions of y are in arithmetic progression with common difference 2 Here a=−19,d=2,tn=13 tn=a+(n−1)d −19+(n−1)(2)=13 (n−1)2=32⇒n=17 Hence number of pairs integers is 17