Question 304834
k = Krity's present age
d = Danny's present age
:
Write an equation for each statement:
:
In one year krity will be four rimes as old as danny.
k+1 = 4(d+1)
k + 1 = 4d + 4
k = 4d + 4 - 1
k = 4d + 3
:
ten years from then krity will be twice as old as danny.
That will be 11 yrs from their present ages
k + 11 = 2(d + 11)
k + 11 = 2d + 22
k = 2d + 22 - 11
k = 2d + 11 
:
Replace k with (4d+3) (from the 1st equation)
4d + 3 = 2d + 11
4d - 2d = 11 - 3
2d = 8
d = {{{8/2}}}
d = 4 yrs
:
Find k using the 1st equation
k = 4(4) + 3
k = 16 + 3
k = 19 yrs is Krity's age
;
:
Check solution in the 1st original equation
k + 1 = 4(d + 1)
19 + 1 = 4(4 + 1)
20 = 4(5)