Evaluating Algebraic expressions with variables word problems

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We can have a good understanding of evaluating expressions with variables with the help of following examples:

Example: The price Regina pays to visit the vet’s clinic is calculated according to the formula 20 + 50n. Here n is the number of times she visits him in a year. This time it was 2. What was the cost of his visit?

Equation here says:  20 + 50n

= 20 + (50.n)

= 20 + (50 × 2)

= 20 + 100

= $120 (Answer)

The expression 10g, tells the number of miles a car can travel using g liters of gasoline.

How far can this car travel on 10\frac{1}{2}  litres of gasoline?

Solution: 10g is the expression

= 10. 10\frac{1}{2}

= 10 × \frac{21}{2}

= 5 × 21

= 105 miles (Answer)

Check Points

  1. The expression is 3f + 23, where f is 10. What is the value of the expression?
  2. What is the pocket money Hilly receives in a week if she gets 5w + 12, where w is $10?
  3. Kim runs a food truck. The expression 25s + 2hgives the cost of s sandwiches and h hot dogs. Find the cost of 3 sandwiches and 7 hot chocolates.
  4. In a School sports day, the number of points the 8th grade team scores is given by 3x + 2y + 1zxis the red team; y is yellow team, and z is the blue team. What is the total number of points scored by 10th graders when red scores 3 three points, yellow 5 points, and blue 2 points?
  5. The expression 7w + 200 litres are the water level which drops in a particular reservoir in a day. Calculate the water level if today is the 5th day.

Answer Key

  1. $53
  2. $62
  3. $20.75
  4. 21 points
  5. 235 litres