Search 74,210 tutors
FIND TUTORS
Ask a question
0 0

-25=r/3-11

Tutors, please sign in to answer this question.

3 Answers

Hi Laura,

When you solve for a single variable in a simplified equation like this one you perform "reverse" operations (undue subtraction with addition and undue division with multiplication) on both sides of the equation until you've "isolated" the variable (which in this case is r). You also need to do the operations in the reverse order that you would if you were simplifying an expression.

In this case we start with:

-25 = r ÷ 3 - 11

First add 11 to both sides to cancel out the "-11":

-25 + 11 = r ÷ 3 - 11 +11    (11's on the right cancel)

     -14    = r ÷ 3

Then multiply both sides by 4 to cancel out the  "÷3"

      -14 * 3 = r ÷ 3 * 3

       -42 = r

So the answer appears to be -42. You can plug -42 in for r to double check your answer (if you want to be sure you made no mistake - always a good idea):

-25 = r ÷ 3 - 11   (now replace r with -42)

-25 = -42 ÷ 3 - 11 (when simplifying one side of the equation division comes before subtraction)

-25 =     -14 - 11   = -14 + (-11) (now add -11 from -14)

-25 = -25

so you can see that when you substitute -42 for r your equation makes a true statement. This confirms your answer as:

r = -42

 

-25=r/3-11

The first step is to combine whole numbers; add 11 to both sides

-25+11=r/3 + -11 + 11

-14=r/3

now multiply each term by 3

-14*3= (r/3)3

-42=r

r=-42

check your answer

-25= -42/3 -11

-25= -14-11

-25=-14 + -11

-25= -25 (true)

Woodbridge algebra tutors