Question 1105106
Let {{{ a }}} = price in dollars/kg for flour
Let {{{ b }}} = price in dollars/kg for sugar
------------------------------
(1) {{{ 3.6a + 1*b = 11.2 }}}
(2) {{{ 5a + 2.5b = 20 }}}
---------------------------
(1) {{{ 36a + 10b = 112 }}}
and
(2) {{{ 50a + 25b = 200 }}}
--------------------------
(1) {{{ 18a + 5b = 56 }}}
(2) {{{ 2a + b = 8 }}}
Multiply both sides of (2) by {{{ 5 }}} and
subtract (2) from (1)
(1) {{{ 18a + 5b = 56 }}}
(2) {{{ -10a - 5b = -40 }}}
-------------------------
{{{ 8a = 16 }}}
{{{ a = 2 }}}
and
(2) {{{ 2a + b = 8 }}}
(2) {{{ 2*2 + b = 8 }}}
(2) {{{ b = 4 }}}
--------------------
flour is $2/kg
sugar is $4/kg
--------------------
check:
(1) {{{ 3.6a + 1*b = 11.2 }}}
(1) {{{ 3.6*2 + 1*4 = 11.2 }}}
(1) {{{ 7.2 + 4 = 11.2 }}}
(1) {{{ 11.2 = 11.2 }}}
You can check (2)