.
The condition is translated to these two equations
F + 10 = 2*(D + 10), (1)
F - 10 = 6*(D - 10). (2)
To solve them, express F = 6D - 50 from (2) and then substitute it into equation (1). You will get
(6D-50) + 10 = 2D + 20,
6D - 40 = 2D + 20 ====> 4D = 60 ====> D = = 15.
Answer. The daughter is 15 years old now; the father is F = 6D - 50 = 6*15 - 50 = 90 - 50 = 40 years old now.
Solved.
There is a bunch of lessons on age word problems
- Age problems and their solutions
- A fresh formulation of a traditional age problem
- Really intricate age word problem
- Selected age word problems from the archive
in this site.
Read them and become an expert in solving age problems.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this online textbook under the topic "Age word problems".