The perimeter of a rectangular field is 628m. The length of the field exceeds its width by 6m. Find the dimensions.

Problem 2

Paula is 12 years older than her brother Bob.  Four years from now Bob will be twice as old as Paula. How old are they now?

Write the problem
2l + 2w = 628
l - 6 = w

Solve for one of the variables (i chose L)

l - 6 + 6 = w + 6
l = w + 6

Solve for one of the equations

2(w+6)+ 2w = 628
2w + 12 + 2w = 628
4w + 12 = 628
4w/4 = 616/4
w = 154

Substitute to find the other variable

l - 6 = 154
l = 160

Answer

l=160
w=154

Problem 2

Write the problem

P - 12 = B
P-4=(B-4)1/2

Solve for one of the variables 

P - 12 + 12 = B
P = B + 12

Solve for one of the equations

B + 12 - 4 = 1/2B - 2
B + 8 = 1/2B - 2 
1/2B = -10
B = -5