Question 1059862
l = 4w -4
l+w=42/2=21 
guess and Check:
w= 5? 5*4=20-4=16 5+16=21 yes
w= 4? 4*4=16-4=12 4+12=16 no
w= 3? 3 *4=12-4=8 3+8=11 no
length=16 in.
width=5 in.