Question

Prove algebraically that each expression has the same value by evaluating each expression for y=5:

7(3−5)−2(10+4) 13−55
(Show each step of your work on its own line)

Answer 1

See explanation

Explanation:

Given two expressions

`7(3y-5)-2(10+4y)`

and

`13y-55`

Substitute y = 5 into each expression:

1.

`7(3y-5)-2(10+4y)\\ \\=7(3\cdot 5-5)-2(10+4\cdot 5)\\ \\=7\cdot (15-5)-2\cdot (10+20)\\ \\=7\cdot 10-2\cdot 30\\ \\=70-60\\ \\=10`

2.

`13y-55\\ \\=13\cdot 5-55\\ \\=65-55\\ \\=10`

As you can see the results are the same.