Answer:
The son is 20
The man is 60
Step-by-step explanation:
We can set up this equation with what we know. Let <em>m</em> stand for the Man's current age, and let <em>s</em> stand for his son's current age.
We know the Man's current age is three times that of his son, so this equation can be written as: <em>m = 3s</em>
Ten years ago means the man's current age <em>minus</em> 10 years. So it is <em>m-10</em>. So ten years ago he was 5 times his son's age 10 years ago, <em>5(s-10)</em>
This can be written as: <em>m-10=5(s-10)</em>
Solve with either substitution or elimination, the choice is yours, it doesn't really matter which method you use. I'll be using substitution.
<em>m-10=5(s-10)</em>
<em>3s-10= 5s-50</em>
<em>40=2s</em>
<em>20 = s</em>
The son is <em>20</em> years old.
We know the man is currently 3 times his son's age, because <em>m=3s</em>, so just solve for m since you now know the value of <em>s.</em>
<em>m=3s</em>
<em>m=3(20)</em>
<em>m=60</em>
The man is <em>60</em> years old
Check the picture below, notice those three quadrilaterals, bearing in mind that a square and rhombus both have equal sides all around.
Answer:
C
Step-by-step explanation:
ley y = f(x) and rearrange making x the subject
y = 
- 1 ( add 1 to both sides )
y + 1 = ( multiply both sides by (x + 5)
(y + 1)(x + 5) = 1 ← expand factors using FOIL
xy + 5y + x + 5 = 1 , that is
xy + x + 5y + 5 = 1 ( factor first/second and third/fourth terms on left side )
x(y + 1) + 5(y + 1) = 1 ← factor out (y + 1) from each term on left side
(y + 1)(x + 5) = 1 ( divide both sides by (y + 1) )
x + 5 = 
( subtract 5 from both sides )
x = - 5
Change y back into terms of x with x = 
(x) , then
(x) = 
- 5 where x ≠ - 1
