Question 262825
The length of a mailing label is 5 cm less than the width
translates as
(i) {{{L = W - 5}}}
we also know
(ii) {{{50 = 2L + 2W}}}
substitute (i) into (ii) to get
(iii) {{{50 = 2(w-5) + 2w}}}
distribute and simplify the right to get
(iv) {{{50 = 4w -10}}}
add 10 to both sides to get
(v) {{{60 = 4w}}}
divide by 4 to get
(vi) {{{w = 15}}}
this means the length is
{{{L = 10}}}
the envelope is 10 x 15