Question

Byron is 3 years older than Doug. The product of their ages is 40.
How old is Doug?

Answer 1

\[B=D+3\text{ yr}\]
\[B\times D=40\text{ yr}\]

Answer 2

b=3+d; b*d= 40 => (3+d)*d=40 => d^2+3d-40=0 => d= -8, 5. So Doug is 5.

Answer 3

I still dont get it

Answer 4

Which part?

Answer 5

do you understand how to get the two equations from the question/

Answer 6

b times d is 5 times 8 right

Answer 7

combining the two equations\[B\times D=40 \text{ yr}\]
\[(D+3\text{ yr})\times D=40 \text{ yr}\]
\[D^2+3D=40\]
\[D^2+3D-40=0\]
\[(D+5)(D-8)=0\]
\[D=-5,8\]

Answer 8

still dont get it man smh its hard to understand

Answer 9

Let Dougs age = x yrs
Therefore Byron = (x + 3) yrs
Multiply the two ages to get 40: x(x + 3) = 40
x^2 + 3x - 40 = 0 after simplifying
(x+8)(x-5) = 0 after factorising
x = -8 or x = 5
But age cannot be negative therefore he is % yrs old

Answer 10

I mean 5 years old (not % yrs old)

Answer 11

this helps thanks