Answer:
10 years
Explanation:
Let x be the number of years we need to add
We want same to be 5 times older than his niece
50 +x = 5(2+x)
Distribute
50+x = 10 +5x
Subtract x from each side
50+x-x = 10+5x-x
50 = 10+4x
Subtract 10
50-10 = 4x
40 = 4x
Divide by 4
40/4 =4x/4
10 = x
In 10 years