Eighty-seven decreased by three times a number is greater than one hundred sixty-five

This is the concept of algebra, we are required to find a number,x, such that 87 decreased by three times a number is great than one hundred and sixty-five.

Supposed the number is x, three times the number will be:
3*x=3x
thus;
87-3x≥165
-3x≥165-87
-3x≥78
dividing both sides by -3 we get:
(-3x)/(-3x)≥78/(-3)
x≤-26
This implies that the number is less than or equal to 26

If you need an equation, it would be y=2x+8, y would be how long it grew, x being weeks.if you need how long he was asleep, it would be 4 weeks if he started with no beard, the equation would be x=8÷2if he did have a beard before hand, the equation would be 2w+x=8