Question 937273
(1) {{{ g +s = 17 }}}
(2) {{{ s + p = 20 }}}
(3) {{{ g + p = 21 }}}
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Subtract (2) from (3)
(3) {{{ g + p = 21 }}}
(2) {{{ -s - p = -20 }}}
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{{{ g - s = 1 }}}
Add (1) and this result
{{{ g +s = 17 }}}
{{{ g - s = 1 }}}
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{{{ 2g = 18 }}}
{{{ g = 9 }}}
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{{{ g - s = 1 }}}
{{{ 9 - s = 1 }}}
{{{ s = 8 }}}
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(2) {{{ s + p = 20 }}}
(2) {{{ 8 + p = 20 }}}
(2) {{{ p = 12 }}}
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Sam spent $8
Greg spent $9
Pedro spent $12
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check:
(1) {{{ g +s = 17 }}}
(1) {{{ 9 +8 = 17 }}}
{{{ 17 = 17 }}}
OK
(2) {{{ s + p = 20 }}}
(2) {{{ 8 + 12 = 20 }}}
{{{ 20 = 20 }}}
OK
(3) {{{ g + p = 21 }}}
(3) {{{ 9 + 12 = 21 }}}
{{{ 21 = 21 }}}
OK