Question 269920
we start with
(i) {{{7(2-(3+4r))=-9+2(1-5r)}}}
first 2-(3+4r) is -1 - 4r
we get
(ii) {{{7(-1-4r) = -9+2(1-5r)}}}
distribute the 7 and then the 2 to get
(iii) {{{-7 - 28r = -9 + 2 - 10r}}}
simplify the right to get
(iv) {{{-7 - 28r = -7 - 10r}}}
the -7's cancel so we get
(v) {{{-28r = -10r}}}
adding 28r we get
(vi) {{{18r = 0}}}
and then r = 0.