This is called the Pythagorean theorem : a ² + b ² = c ². You can substitute any of the variable with any of the known numbers and then you all you have to do is isolate the variable. I hope that helps!!
So, what you would have to do is figure out how old he is not which is 30 yrs old because it is half of 60.
So, after this you would have to find a number that would go into 60 four times which is 15.
So, your answer would be 15.
HOPES THIS HELPS!!!!
The first one is additive
the second one is additive
the third one is multiplicative
the last one is multiplicative
Answer:


Step-by-step explanation:












Length=5 (each side)
width=5 (each side)