*will mark brainliest* adam and barb had a used book sale over the weekend. adam sold 4 hardcover books and ten paperbacks and earned $64 for his efforts. barb sold 5 hardcover books and 7 paperbacks for the same prices each. barb made $58. adam and barb both charged the same price for the hardcover books and the same price for the paperbacks. how much did they charge for hardcovers and how much for paperbacks? 1. mathematically what kind of problem is this? what skill or concept did we learn in this unit which, when applied to this problem, will allow you to solve the problem? 2. set up the problem showing the equations you’ll use. be sure to label or explain what your variables mean. 3. show the math work to arrive at the answer. write and mark your final answer. be sure to make it clear which is hardcover and which is paperback. * you so much*

The text itself determined how to solve the problem.

Namely, two object are given in two relations and we conclude that we have two variables that we present with two equations.

We will take hardcover books as x and paperbacks as y.

First equation is  4x+10y=64

Second equation is  5x+7y=58

This is system of two linear equations with two variables

To solve this system we will use Gaussian agorithm with which we make

gradual elimination of the variables.

We will multiply first equation with number 4 and second with number (-5)

and get

20x+50y=320   and   -20x-28y=-232

When we add first equation to another we get

variable x is eliminated  

50y-28y=320-232 => 22y=88 => y=88/22=4

y=4  when we replace variable y in the first equation before multiplying

we get  4x+10*4=64 => 4x+40=64 => 4x=64-40 => 4x=24 => x=24/4=6

x=6

Total charge for hardcovers is  => 4x+5x=9x=9*6=54$

Total charge for paperbacks is => 10y+7y=17y=17*4=68$

Good luck!!!

225x²+4=0

225x²=0-4

225x²=-4

x²=-4/225

x=±√-4/225