Question 602457
Supplementary means they add up to 180 degrees
Let the angles be {{{ a }}} and {{{ b }}} degrees
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(1) {{{ a + b = 180 }}} degrees
(2) {{{ a = 3b + 10 }}} degrees
Substitute (2) into (1)
(1) {{{ 3b + 10 + b = 180 }}}
(1) {{{ 4b = 170 }}}'
(1) {{{ b = 42.5 }}}
and
(1) {{{ a + b = 180 }}}
(1) {{{ a + 42.5 = 180 }}}
(1) {{{ a = 137.5 }}}
check:
(2) {{{ a = 3b + 10 }}}
(2) {{{ 137.5 = 3*42.5 + 10 }}}
(2) {{{ 137.5 = 127.5 + 10 }}}
(2) {{{ 137.5 = 137.5 }}}
OK