Have I done this correctly?
Suppose that the water level of a river is 34 feet and that it is receding at a rate of 0.5 foot per day.
a. Write an equation for the water level, L, after d days.
L = -.5d + 34
b. In how many days will the water level be 26 feet?
26 = -.5(d) + 34
26 – 34 = -.5(d)
-8 = -.5d
16 days
Yes, you have done it correctly.
To solve part a, you correctly wrote the equation L = -0.5d + 34. This equation represents the water level, "L", after "d" days, where the water level is decreasing at a rate of 0.5 feet per day. The initial water level is given to be 34 feet.
To solve part b, you substituted 26 feet for L in the equation L = -0.5d + 34. You then simplified the equation and solved for "d" by subtracting 34 from both sides. This resulted in -8 = -0.5d. Finally, you divided both sides of the equation by -0.5 to isolate "d", and found that d = 16 days.
Therefore, after 16 days, the water level will be at 26 feet, according to the given rate of recession. Well done!