Question 921962
Let we assume that shirin is X years old, and her father is Y years old.
At, present the equation is y=4x......(1)
after 18 years age of shirin and her father will increase by 18 years, hence we can write an equation after 18 years is (y+18)=2(x+18)......(2)
now put y=4x in equation (y+18)=2(x+18)
so, (4x+18)=2(x+18)
     4x+18=2x+36
     4x-2x=36-18
        2x=18
         x=9

here, x=9 put in an equation (1).
so, y=4x
    y=4(9)
    y=36
we have found out that shirins's current age is 9 years and her father's current age is 36 years.