Carlos is saving up to buy two new books. he has saved 60% of one book that costs 18$, and 30% of the cost of another book that costs 21$. how much more does he need to save?

The answer to your question is: $61

Step-by-step explanation:

Data

Book 1 = 60% that costs $18

Book 2 = 30% that costs $21

Process

        Book 1

                          60% $18

                       100 %      x

                          x = (100x 18)/60 = $30 actual cost

                      He needs to save 30 -18 = $12

     Book 2

                      30%  $21

                     100%   x

                      x = (100 x 21) / 30 = $70 is the actual cost

                   He needs to save 70 - 21 = $49

Total

             $49 + $12 = $61 needs to save to buy two books

-2x + 7 = 7

subtract 7 from both sides.

-2x = 0

divide both sides by -2.

x = 0