# a+3=(2a+7)÷r. # How do you make a the subject of the formula?

1 Answer
Apr 12, 2018

#a = (7-3r)/((r-2))#

Explanation:

#a+3 = (2a+7)/r" "larr# multiply both sides by #r#

#color(blue)(rxx)(a+3) = color(blue)(cancelrxx)(2a+7)/cancelr#

#" "ar +3r= 2a+7" "larr# there are two #a# terms#

#" "ar -2a = 7-3r" "larr# re-arrange the #a# terms on one side

#a(r-2) = 7-3r" "larr# factorise

#(acancel((r-2)))/cancel((r-2)) = (7-3r)/((r-2))" "larr# divide both sides by #(r-2)#

#a = (7-3r)/((r-2))#