SAT 代数与高等数学练习题

Algebra / Linear Equations One Variable

Linear Equations from Contexts

Context problems often require defining a variable, writing a one-variable linear equation, and interpreting the solution in the original situation.

Least you need to know

  • Identify the fixed amount, rate, and total before writing an equation.
  • Use units to decide whether to multiply, divide, add, or subtract.
  • After solving, check that the value answers the specific question asked.

Key notation

  • $6+2.5m=31$ — A fixed fee plus a per-unit rate equals a total

Worked example

  • If a service costs $10 plus $4 per hour and the total is $34, write $10+4h=34$.
  • Subtract 10: $4h=24$.
  • Divide by 4: $h=6$.

Common mistakes

  • The variable should represent the quantity requested.
  • A percent discount or increase usually requires a multiplier.

How to recognize it

  • The problem gives a total and a rate.
  • The problem describes a fixed cost plus a variable cost.
  • The answer is one unknown number.

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