"Seven years ago i was eleven times my daughters age, now i am four times my daughters age" How old is he

Question

Show me howtosolve .Its for precalculus. The answer is that he is 40 years old but i dont know how to get to it

The answer is that he is 40 years old but i would like to see a problem step by step with x as a variable in an equation.

Answer 1

f(i) = 11d
f(today)=f(i)+7=4(d+7)
=>f(i)+7=4d+28
=>f(i) = 4d + 28 -7
since f(i) = 4d +21 and 11d
=> 4d + 21 = 11d
=> 21 = 7d so d = 3 (age of daughter 7 years ago)
f(today) = 4 (d + 7)

Answer 2

Start by writing equations that describe the facts you have:
(let p be the parent's age; let d = the daughter's age)

You know that
p - 7 = 11 (d - 7).........(parent's age 7 years ago equals 11 times daughter's age 7 years ago)
and
4 d = p....................(parent's age is four times daughters)

Modify the second equation a little bit to make it more useful:
d = p / 4

Now substitute the second equation into the first:
p - 7 = 11(p/4 - 7)

Now use what you know about algebra to solve the equation for p.

Answer 3

He is 40...she is 4. Just look at the two equations

y=11*x and y+7=4(x+7)

and solve them simultaneously. That is, substitute 11*x in for y in the second equation and solve for x. You'll get 3, which will imply that y=33, which means he's 33+7=40 now.

Answer 4

Let x be his current age.
Let y be the daughters.

Therefore 7 years ago he was x-7 and the daughter y -7.

From the first statement,
x - 7 = 11 * (y - 7)

From the second statement,

x = 4 * y.

Solving both equations:

x = 40 and y = 10.

Answer 5

you * 11 = daughter
(you+7) * 4 = daughter +7\

11y=d
4(y+7)=d+7
so, 4y +28 = d+7
subtract 7 from both sides
4y +21 = d
now you have 2 equations for d so set them equal to each other
11y = 4y +21
now solve for y
7y = 21 so y=3
put that into the now equation
4*(3+7)=d +7 therefore you are 40

Answer 6

x = you today
y = daughter today

For 'seven years ago' you get this equation
x minus 7 years = 11 times y minus 7 years
also written as x-7 years = 11*(y-7 years)
also written as x-7 = 11(y-7)
multiply 11 through y-7..........x-7 = 11y-77
move -77 over to x side...........x+70 = 11y

For 'today' you get this equation
x = four times y
also written as x = 4*y
also written as x = 4y

Now substitute 4y for x in the first equation (x+70 = 11y)
4y+70 = 11y

Now solve for y
70 = 11y - 4y
70 = 7y
70/7 = y
10 = y

So if y = 10 and x = 4y
then x = 4(10)
x = 40

Answer 7

If the daughter changed from a she to a he all of a sudden i think that there are more problems in this family than age! but then again anything is possible in today's world and maybe this question is simply politically correct!

Answer 8

40 now. Seven years ago, he was 33 and she was 3. Now, he is 40 and she is 10.

Answer 9

x= age of daughter (11)
y = age of father (40)
y/x = years in prison (3.333...)

Answer 10

Scott is Correct!