Dad and Xiao Li are 58. Dad is 25 years older than Xiao Gang. Xiao Gang is 3 years older than Xiao Li. How old are Dad, Xiao Li and Xiao Gang

Dad and Xiao Li are 58. Dad is 25 years older than Xiao Gang. Xiao Gang is 3 years older than Xiao Li. How old are Dad, Xiao Li and Xiao Gang

Let father x, Xiao Li Y, Xiao Gang Z, (1) x + y = 58 (2) x-z = 25 (3) Z-Y = 3
The elimination method is used to calculate: first eliminate x, (1) - (2) to get: y + Z = 33, then eliminate y, (2) + (3) to get: 2Z = 36, z = 18
Finally, y = 15, x = 43
Dad is 43, Xiao Li is 15 and Xiao Gang is 18