Question 1121008

when the father was the same age as his daughter is now, she was 4 years old. when the daughter becomes the same age as her father is now, her father will be 79 years old. what are their ages
<pre>Let the daughter’s and father’s ages be D, and F, respectively
Then difference in ages = F – D
We then see that: D – (F – D) = 4_____D – F + D = 4____2D – F = 4_____F = 2D – 4 ---- eq (i)
Also, we see that F + (F – D) = 79_____2F – D = 79 ----- eq (ii)
2(2D – 4) – D = 79 ------- Substituting 2D – 4 for F in eq (ii)
4D – 8 – D = 79
4D – D = 79 + 8
3D = 87
D, or daughter is: {{{highlight_green(matrix(1,4, 87/3, "=", 29, "years-old"))}}}
Father’s age: {{{highlight_green(matrix(1,3, 2(29) - 4, "=", 54))}}}