Explanation:
Let the numbers be
and

Given, difference between the squares of two numbers is 24. Assuming |x| > |y|,

Now the second part of the question: Four times the square of the first number increased by the square of the second number is 101. In equation form,

Adding these two equations,
=> x² - y² + 4x² + y² = 125
=> 5x² = 125
=> x² = 25
=> x = ±5
Then y will be,
=> {(+/-5)² - y² = 24)
=> 25 - y² = 24
=> y² = 1
=> y = ± 1
The set of solutions for (x,y) that are possible: (5,1), (5,-1), (-5,1) and (-5,-1).
Note:
The assumption we took earlier |x| > |y| is because square of whether positive or negative values of x and y will always be positive. Hence what matters to us was the numerical value of magnitude of x and y.