Algebraic Expressions
four less than a number
x-4
5+x=20
15
5x=40
x=8
x/4=5
x=20
A growing tree absorbs about 26 lb of carbon dioxide each year. How many years will the tree take to absorb 390 lb of carbon dioxide?
15 yrs
4/x
50-x=10
40
9x=-81
x=-9
20/x=2
x=10
A hardcover book costs $19 more than its paperback edition. The hardcover book costs $26.95. How much does the paperback cost?
x+19=26.95
x=26.95-19
x=$7.95
three times a number
3x
-10-x=-14
4
19x=114
x=6
-10/x=5
x=-2
A basketball player scores 15 points in one game and p points in a second game. Her two-game total is 33 points. Write and solve an equation to find the number of points scored in the second game.
15+p=33
p=33-15
18 points
nine more than a number
x+9
63+x=47
-16
-4x=68
-17
x/3=-12
x=-36
The chemical element aluminum was discovered in 1825 by Hans Christian Oersted. This was 18 years after Sir Humphry Davy discovered the element sodium. Write and solve an equation to find the year that sodium was discovered.
y+18=1825
y=1825-18
y= 1807
The year was 1807
the quotient of 6 and a number
6/x
47-x=59
-12
-52x=208
x=-4
-460/x=-92
x=5
You are starting a savings account. You make an initial deposit of $100. Every week after that, you deposit $20. Your goal is to save $1,000. Write an algebraic equation and find how many weeks you will need to reach your goal.
100+20w+1,000.
45 Weeks