How do you simplify: 2 radical 50- 3 radical 8

Let A = 2 radical 50- 3 radical 8 
 radical 50 = sqrt( 2* 25 ) = 5sqrt( 2 )
 radical 8  = sqrt(2*4) = 2 sqrt(2)
so 
A = 2 radical 50- 3 radical 8 = 10sqrt( 2 ) - 6sqrt( 2 ) = 4sqrt( 2 )
finally 

A = 4sqrt( 2 )

If you need an equation, it would be y=2x+8, y would be how long it grew, x being weeks.if you need how long he was asleep, it would be 4 weeks if he started with no beard, the equation would be x=8÷2if he did have a beard before hand, the equation would be 2w+x=8