given d =
multiply both sides by (y + n)
d(y + n) = m - y ← distribute left side
dy + dn = m - y ← add y to both sides
dy + y + dn = m ← subtract dn from both sides
dy + y = m - dn ← factor out y on the left side
y(d + 1) = m - dn ← divide both sides by (d + 1)
hello from mrbilldoesmath!
the attachment shows a right triangle where arcsin(@) = 1/4. (the arcsin means find the angle whose sine is 1/4 as is done in the triangle.) the missing side, sqrt(15), shown in red, was determined by the pythagorean theorem.
then cos(@) = cos(arcsin(1/4)) = sqrt(15)/4
so per week, 7 hours on internet, and 13 playing games.
we can combine these two values, as they're both a part of the answer.
7 + 13 = 20
so, gary has 5 hours a day.
7 days in a week, so 5 * 7 = 35
that means 35 hours of free time a week.
so, time spent on the internet and video games can be represented as 20/35
to find the percentage, we can just divide.
20/35 = 0.57, or 57%
57% of free time is spent playing video games