Two natural numbers differ by 4 and the sum of their squares is 58 find the numbers?

The firs number: a

The second number: b

a-b=4

a²+b²=58

Lets write b+4 instead of a.

(b+4) ² + b² = 58

b²+8b+16+b²=58

2b²+8b+16=58

2b²+8b-42=0

b²+4b-21=0

(b+7). (b-3) = 0

b=-7 or b=3

But, b can't equal to - 7 because these number are naturel numbers. It must be positive.

b=3

for b=3; a-3=4; a=7