Question

Kathy is 6 years younger than Bill. Twelve years ago, Bill was twice as Kathy was then. How old are they know?

Answer 1

k = b - 6

2(k - 12) = b-12


2k -24 = b-12
2k = b-12+24
2k = b + 12

//substitute
2(b - 6) = b +12
2b - 12 = b +12
2b = b +24
b = 24


/substitute in original

k = b - 6
k = 24-6
k = 18
24 and 18


12 years ago
24-12 and 18-12
or
12 and 6

Answer 2

Let k and b be Kathy's and Bill's current age respectively. Solve the following equations for k and b:\[\left\{k=b-6, \frac{b-12}{k-12}=2\right\}\]\[\{k=18,b=24\} \]