how muchis one pen when 3 is $4.50

Answer 1

a variable is simply an unknown value which we can find out

if some variable which we call x is the cost of one pen

and the cost of 3 pens or 3x is $4.50

then we can say that

3x=4.50 or 3(cost of one pen)=4.50

we can divide both side by three to get:

(cost of one pen)=4.50/3 or (cost of one pen)=1.50

this can also be written as

x=4.50/3 or x=1.50

equation manipulation is described below:

since this is an equation and both side are equal to each other, if we perform a math operation on one side of the equation we must also do it to the other side

for exampe: if 1 apple = 1 apple and we subtract 1 apples from both sides of the equation

we get 0 apples=0 apples which is true

if we only did it to one side of the equations: both sides would not be equal to each other and the equation would not be true

for example: if 1 apple= 1apple and we subtract 1 apple from the left side but not the right side

we get 0 apples = 1 apple which is not true