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Exercises Equations and inequalities

Example 8.21 from Prealgebra, 8.3 Solve Equations with Variables and Constants on Both Sides

Solve Equations with Variables and Constants on Both Sides: example 8.21

Solve: $2 y - 7 = 15 .$

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Solution
Notice that the variable is only on the left side of the equation, so this will be the variable side and the right side will be the constant side. Since the left side is the variable side, the $7$ is out of place. It is subtracted from the $2 y,$ so to ‘undo’ subtraction, add $7$ to both sides.

Add 7 to both sides.

Simplify.

The variables are now on one side and the constants on the other.

Divide both sides by 2.

Simplify.

Check:

Substitute: $y = 11$ .

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

Solve: $5 y - 9 = 16 .$

How did it go?

PreviousSolve Equations with Variables and Constants on Both Sides: example 8.20 Next Solve Equations with Variables and Constants on Both Sides: example 8.22

From Prealgebra (1st edition) by OpenStax (Rice University), section 8.3, licensed under CC BY 4.0. Original at openstax.org. We split the solution into steps; the words, numbers and figures are the book's. OpenStax doesn't endorse this site.