Make an equation system based on the problem
Jason and Mara have $74
⇒ j + m = 74
Jason has $6 more than 1/3 as much money as Mara has
⇒ j = (1/3)m + 6
Then, solve the equation by subtitution
j + m = 74
(1/3)m + 6 + m = 74
(1/3)m + m = 74 - 6
(1/3)m + (3/3)m = 68
(4/3)m = 68
m = 68 ÷ 4/3
m = 68 × 3/4
m = 51
Mara has $51
j + m = 74
j + 51 = 74
j = 74 - 51
j = 23
Jason has $23