Question 1140123
distance=speed*time
yacht=x speed
speedboat=2x speed

so 150=x*t1
240=2x*(t1-1)
300=2x*t1, multiplying the top by 2
240/(t1-1)=300/t1
cross-multiply
240 t1=300t1-300
-60 t1=-300
t1=5 hours for yacht and speed is 30 mph
t2=4 hours for speedboat and speed is 60 mph