In order to rearrange the equation so that r is the independent variable is the same thing as making r the subject of the formula from the given expression
q-10= 6(r+1)
we say,
q - 10 = 6r + 6 ( by using 6 to open the bracket)
we are going to collect the like terms
q- 6r = 6 + 10
q- 6r = 16
q = 16 + 6r
q-16 = 6r
divide both sides by the coefficient of r which is 6
