60=l*w implies w=60/l
38=2l+2w
substitute w the equation for w into the second equation:
38=2l+2*60/l
38=2l+120/l
19=l+60/l
19l=l^2+60
0=l^2-19l+60
0=(l-15)(l-4)
gives l=15 or l=4
From the first equation, 16=4w implies 4=w.
The dimensions are 15x4.
Check:
15*4=60
15*2+4*2=30+8=38