Question 70028
1. Use the formula for a perimeter:
Perimeter = 2(Length + Width)
P=2(L+w)
P=600
L=L
w=L-30
.
P=2(L+w)
600=(2(L+(L-30)) [plug-in the values]
600=2(2L-30) [simplify]
600/2=2(2L -30)/2
300=2L-30
300+30=2L-30+30
330=2L
330/2=2L/2
165=L
.
Since the Width = Length -30, 
Than, Width = 165-30=135
.
Check by plugging-in all of the values back into the original formula:
P=2(L+w)
600=2(165+135)
600=2(300)
600=600 [checks out]
.
.
2. Solve and write in interval notation for the solution set
-5 <_ 2x + 1 < 7[isolate the x variable]
-5-1 <_ 2x + 1-1 < 7-1
-6 <_ 2x  < 6
-6/2 <_ 2x/2  < 6/2
-3 <_ x  < 3
.
[-3, 3)