Question 433086
Let {{{a}}} = cost of sandwich
Let {{{b}}} = cost of hamburger
given:
(1) {{{ 7a + 4b = 34.5 }}}
(2) {{{ 3a + 8b = 30.5 }}}
-----------------
Multiply both sides of (1) by {{{2}}}
and subtract (2) from (1)
(1) {{{ 14a + 8b = 69 }}}
(2) {{{ -3a - 8b = - 30.5 }}}
{{{ 11a = 38.5 }}}
{{{ a = 3.5 }}}
Plug this back into (1) or (2)
(2) {{{ 3*3.5 + 8b = 30.5 }}}
{{{ 10.5 + 8b = 30.5 }}}
{{{ 8b = 20 }}}
{{{ b = 2.5 }}}
The cost of a sandwich is $3.50
The cost of a hamburger is $2.50