Please help!

i dont get this

If you shift the linear parent function, f(x)=x, up 13 units, what is the equation of the new function?

What is the value of x in the equation 2(x-4) = 4(2x + 1)?

How many liters of peroxide should be added to 12 liters of an 8% peroxide solution so that the resulting solution contains 16% peroxide?   original added new amount of peroxide 0.96 liters x 0.96 + x amount of solution 12 liters x 12 + x 0.18 liter 1.14 liters 1.92 liters 2.10 liters