Question 1102851
mara is eight years older than clara. three years age, mara's age is thrice (three times) clara's age. 


what is the present age of mara?


let m = mara's age today.
let c = clara's age today.


your equations are:


m = c+8
m-3 = 3*(c-3)


in the second equation, replace m with c+8 to get c+8-3 = 3*(c-3)
simplify to get c+5 = 3c-9
subtract c from both sides of this equation and add 9 to both sides of this equation to get 14 = 2c
solve for c to get c =7


when c = 7, m = c+8 = 15
3 years ago m-3 = 12 and c-3 = 4
12 = 3*4


solution is confirmed to be good because m = c+8 and m-3 = 3*(c-3)