Answer:
$19.6
Step-by-step explanation:
He bought 6 video games and 1 dvd
We know that each video game costs $2.7 and each dvd costs 3.4
To get the sum = v x 6 + d x 1
= 2.7 x 6 + 3.4 x 1
= 16.2 + 3.4
= $19.6
You first wanna find <BAD, because if AB is perpendicular to AC, then it has to form a 90 degree angle. So 90-56=34 degrees. So now you have a 34 & 63 degrees in the ABD triangle. In a triangle, all angles add up to equal 180 degrees. So 34+63+x=180...and x=83. So <ADB= 83 degrees. Now you want to find angle ADC...which you can just subtract 83 from 180 (because <ADB & <ADC forms 180 degree angle). You will then get 97 as angle ADC. So, the same thing as before, add up 56+97+x=180, because all angles (in the triangle ADC) add up to be 180 degrees. X will then equal 27 degrees. Angle ACB= 27 degrees.
So... the radiator has 15 liters of 70% antifreeze.. but needs an 80% antifreeze
well, so, you need to drain some and put some with higher percentage, seems to be, you will end up at the same 15 liters, possible the radiator's capacity, of 80% antifreeze
so, the same amount going out, of 70% is the same amount going in, of 100% antifreeze
now.. let's use the decimal format for the percents, or 70% is 70/100 or 0.7 and so on

so.. let's subtract, from the current solution, 0.7x and add 1x or x, our antifreeze concentration amount, should be 12 though
10.5 - 0.7x + x = 12
solve for "x"