The Pythagorean Theorem formula is listed below. It can only be applied to right triangles.
(side1)^2 + (side2)^2 = (hypotenuse)^2
Since we are given that the base is 8cm, we know that the side of one triangle is 4cm. We are also given that the hypotenuse is 8cm. The height of the cone will be one of the short sides. If we plug these numbers into the formula, we get the following...
... (time spent in video games)/(time spent in television) = (10 minutes)/(1 hour)
However, the intent is to end with a pure number (no units), so we need to convert hours to minutes or vice versa. Most folks know that 1 hour is 60 minutes, so that is probably the easier conversion.
... = (10 minutes)/(60 minutes)
... = 10/60 . . . . . . . . . the units in numerator and denominator are the same, so cancel
... = 1/6 . . . . . . . . . . . .the fraction is reduced in the usual way