Fred cycled from home to his friends house and back again.
The distance is 20km.
On his way home, he cycled x km per hour.
On his way back, his speed decreased by 2km per hour.
It took him 4 hours altogether to cycle to his friends house and back.
1. Write down an equation for x
x = (20/4) - 2 ?
2. Show that the equation can be written as x^2 - 12x + 10 = 0
3. Solve the equation in question 2 to 1 decimal place
4. Only one of teh answers in question 3 can be Freds speed. Explain why.