Question 559138
Let {{{ c }}} = number of cats
Let {{{ b }}} = number of birds
given:
(1) {{{ c + b = 22 }}}
(2) {{{ 4c + 2b = 60 }}}
Multiply both sides of (1) by {{{ 2 }}},
and subtract (1) from (2)
(2) {{{ 4c + 2b = 60 }}}
(1) {{{ -2c - 2b = -44 }}}
{{{ 2c = 16 }}}
{{{ c = 8 }}}
and, since
(1) {{{ c + b = 22 }}}
(1) {{{ 8 + b = 22 }}}
(1) {{{ b = 22 - 8 }}}
(1) {{{ b = 14 }}}
There are 8 cats and 14 birds
check:
(2) {{{ 4c + 2b = 60 }}}
(2) {{{ 4*8 + 2*14 = 60 }}}
(2) {{{ 32 + 28 = 60 }}}
(2) {{{ 60 = 60 }}}
OK