Solve for x in the diagram below.

X= 12 3x+x+42=90 4x+42=90 subtract 42 from each side cancelling out one side 4x=48 then divide by 4 on each side to get the variable by its self x=48

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