AlgebraEasy–MediumReading a linear model at a given input
Algebra practice question
The amount of grain, in kilograms, left in a silo d days after it is filled is modelled by w(d) = 1200 − 45d. How many kilograms of grain are left after 20 days?
Answer: 300
w(20) = 1200 − 45 × 20 = 1200 − 900 = 300.
Common wrong answers
- If you answered 900
- 900 is the amount USED in 20 days, not what is left.
- If you answered 1155
- 1155 subtracts 45 once, as if d = 1.
- If you answered 2100
- 2100 adds 900 instead of subtracting it.
More Algebra questions
- Easy–Medium
A line passes through the points (0, 3) and (2, 7). What is the slope of the line? - Easy–Medium
A gym charges a $25 one-time signup fee plus $15 per month. Which equation gives the total cost C, in dollars,… - Easy–Medium
If 5(x − 2) = 3x + 4, what is the value of x? - Easy–Medium
A taxi charges a $3.50 base fare plus $2.25 per mile. If a ride costs $19.25 total, how many miles was the rid… - Easy–Medium
The equation of a line is 3x + 2y = 12. What is the y-coordinate of the point where the line crosses the y-axi… - Easy–Medium
A line in the xy-plane passes through the points (1, 5) and (4, 11). What is the y-intercept of the line?
Not affiliated with the College Board. SAT is a trademark of the College Board.