Calculating the corresponding percentage

Homework Statement

A car is travelling at initial speed 5.5ms-1. The car is on a decline of 8o. The brakes are used and the car stops after travelling 10m along the road (with no skidding).

At the moment when kinetic energy is 51% lower than the initial value,
ﬁnd the corresponding percentage fall in speed.

Ek = 1/2mv2

The Attempt at a Solution

E is 51% lower, so $$\frac{2(0.49)Ek}{m}$$=v2
Clueless?!

$$\frac{Ek_2}{Ek_1}=\frac{49}{100}$$