A parent is 4 times as old as their child. Together they are 85. How old is each?
The child is 17 and the parent is 68.
How to work it out
- 1
Let x be the child's age. The parent is 4 times as old, so the parent is 4x.
- 2
Together they are 85:
- 3
Combine the x terms and divide:
- 4
The parent is 4 × 17 = 68.
- 5
Check: 17 + 68 = 85 ✓ and 68 = 4 × 17 ✓.
LaTeX source of the formulas on this page
\[ x + 4x = 85\ \Rightarrow\ x = 17 \]
\[ x + 4x = 85 \]
\[ 5x = 85\ \Rightarrow\ x = \frac{85}{5} = 17 \]Questions
How old is the child?
17.
How old is the parent?
68.