If3,x,y,18 are in arithmetric progression , find the value of x and y

Answer 1

x-3 = 18-y

x-3 = y -x
so
x+y = 21
-2x + y = -3
------------
3 x = 24
x = 8
then y = 21-8 = 13

so
3 , 8 , 13 , 18
difference is always 5

Answer 2

Convert 42 base 5 to a base 3 numeral

Answer 3

Thanks very much