What you’ll learn to do: Solve equations with decimals using properties of addition and subtraction

To calculate the difference between two swimmers’ race times, you’ll need to write an equation with decimals.

Kim and Alyssa are on the same high school swim team, and they’re always competing for the fastest time in the 50-meter freestyle event. In the last race, the difference between Kim’s time and Alyssa’s time was 1.36 seconds. If Alyssa swam the race in 36.79 seconds, what was Kim’s time? To solve this problem, you’ll need to translate the information given to an equation and then solve it. Read on to find out more about solving equations with decimals.

Before you get started, take this readiness quiz.

readiness quiz

1)

If you missed this problem, review the example below.

Evaluate [latex]y-\Large\frac{5}{6}[/latex] when [latex]y=-\Large\frac{2}{3}[/latex]

Show Solution

Solution:
We substitute [latex]-\Large\frac{2}{3}[/latex] for [latex]y[/latex] in the expression.

[latex]y-\Large\frac{5}{6}[/latex]

Substitute [latex]\color{red}{-\Large\frac{2}{3}}[/latex] for y.

Prealgebra. Provided by: OpenStax. License: CC BY: Attribution. License Terms: Download for free at http://cnx.org/contents/caa57dab-41c7-455e-bd6f-f443cda5519c@9.757