If 40% of students prefer keyboarding, 40/100*40=16 students like it best. If the remaining students prefer English, then 40-16=24 students like English best. Since 24 is more than 16, most students prefer English.
You just substitute the value of x in the given equation:
f(x) = 2x^2 - 5
f(-4) = 2 (-4)^2 -5 = 27
f(x) : a name given to the equation
f(-4): refer to the equation when the value of the independent variable x has the value between the brackets.
