Question 448753
Let {{{a}}} = number of regular meals
Let {{{b}}} = number of child's meals
given:
(1) {{{ 7a + 5b = 53 }}}
(2) {{{ a + b = 9 }}}
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Multiply both sides of (2) by {{{5}}} and
subtract (2) from (1)
(1) {{{ 7a + 5b = 53 }}}
(2) {{{ -5a - 5b = -45 }}}
{{{ 2a = 8 }}}
{{{ a = 4 }}}
and, since
(2) {{{ a + b = 9 }}}
(2) {{{ 4 + b = 9 }}}
{{{ b = 5 }}}
The number of regular meals is 4
The number of child's meals is 5
check:
(1) {{{ 7a + 5b = 53 }}}
(1) {{{ 7*4 + 5*5 = 53 }}}
(1) {{{ 28 + 25 = 53 }}}
{{{ 53 = 53 }}}