Question

How to do this question?

Answer 1

Remark

Drawing that diagram was a very good idea. If you can picture something happening, you are half way there. I tend to use a table, but the diagram will come to the same thing.

                  Olivia                    Dawn

Start            176                         80

Donate         x                             x      Subtract

What's left   176 - x                  80 - x

Equation

176 - x = 5*(80 - x)     Olivia had 5 times as many books as Dawn did.   Remove the brackets.      

Solution

176 - x = 400 - 5x                 Add 5x to both sides

176 + 5x - x = 400                  Combine terms on the left

176 + 4x = 400                    Subtract 176 from both sides

4x = 400 - 176                     Combine terms on the right.

4x = 224                              Divide by 4

x = 224/4    

x = 56                                 Answer