© it is
J1 = Jason's salary in 1995
J2 = Jason's salary in 1998
K1 = Karen's salary in 1995
K2 = Karen's salary in 1998
(J2 - J1)/J1 = (K2 - K1)/K1
(1) K1 = 2,000 + J1 => insuff
(2) K2 = 2,440 + J2 => insuff
(1) & (2) =>
(J2 - J1)/J1 = (2,440 + J2 - 2,000 - J1)/(2,000 + J1)
=> (J2 - J1)/J1 = (440 + J2 - J1)/(2,000 + J1)
=> 2,000(J2 - J1) + J1(J2 - J1) = 440J1 + J1(J2 - J1)
=> (J2 - J1)/J1 = p = 440/2,000 => suff