We have two moments of history here: "now" and "then" (at particular moment in the past). Let's mark as the following:T - Tom's age nowE - Elizabeth's age nowTo - Tom's age thenEo - Elizabeth's age thenSo we have:T - E = To - Eo (their difference is constant) (1)T + E = 49 (2)T = 2Eo (3)To = E (4)Using (4) into (1): T - E = E - Eo Then using (3) here:2Eo - E = E - Eo 2Eo + Eo = E + E3Eo = 2EE = 3/2 Eo (5)Using (5) and (3) into (2):T + E = 492Eo + 3/2Eo = 49 3 1/2Eo = 497/2Eo = 49Eo = 49 : 7/2Eo = 14So, Elizabeth was 14. It means now Tom is 2*14=28. Elizabeth now is 49 - 28 = 21Answer: Elizabeth is 21, Tom is 28