Answer:
98
Step-by-step explanation:
To find the median cancel out numbers on both sides, until one is left in the middle and if there are two in the middle add them up and divide by two.
So in this case the median is
53+78
131 / 2
65.5
He can make 15 chess boards.
All you need to do is multiply 3 by 5.
(x + 5)(x + 3)
x+5=0, solve it and you get -5.
x+3=0, solve it and you get -3.
The answers are -5 and -3.