HELP! pleasepleaseplease

Question

natalie is 4x years old. her sister, mandy is 3 years older than her. 4 years ago, their total age was 51 years, find natalie's present age.

Answer 1

Let N = 4x

Let M = 4x+3 = N+3

N-4 + M-4 =51

N-4 + N+3 -4 = 51

2N-5=51

2N=56

N = 28