Fill in the blanks; If two amounts are , you can substitute one for the other.
To solve a system of equations, you can replace a with an equal value or expression.
To check a solution, you can the solutions into the equations and verify that both equations are true.
Substitution is the best method to use when one variable is already or when one variable can be easily .

Horace's speedometer reads 60 miles per hour, but during a road test he finds that he was actually driving 58 mph. what is the percent error in horaces speedometer?

George writes the mixed number as sum and uses the distributive property 1/2.-2/5=1/2-2+2/5=1/2

Consider the following geometry problems in 3-space enter t or f depending on whether the statement is true or false. (you must enter t or f -- true and false will not work.) f equation editorequation editor 1. a plane and a line either intersect or are parallel t equation editorequation editor 2. two planes parallel to a third plane are parallel f equation editorequation editor 3. two lines either intersect or are parallel f equation editorequation editor 4. two planes orthogonal to a third plane are parallel f equation editorequation editor 5. two planes orthogonal to a line are parallel f equation editorequation editor 6. two planes either intersect or are parallel f equation editorequation editor 7. two lines orthogonal to a third line are parallel t equation editorequation editor 8. two lines parallel to a third line are parallel t equation editorequation editor 9. two planes parallel to a line are parallel f equation editorequation editor 10. two lines parallel to a plane are parallel f equation editorequation editor 11. two lines orthogonal to a plane are parallel