Question 805554
Time taken by walker - time taken by jogger = 4 hours

let walker speed = x kph
jogger speed = x+4 kph

distance = 30 

t=d/r

30/(x-10)-30/x=4

multiply equation by x(x-10)

30x-30(x-10)= 4x(x-10)

30x+300-30x=4x^2-40x

4x^2-40x-300=0

/4
x^2-10x-75=0

x^2-15x+10x-75=0

x(x-15)+10(x-15)=0

(x-15)(x+10)=0

x=15 OR -10

ignore negative

x=15