Question 878881
Let {{{ a }}} = hours worked for office job
Let {{{ b }}} = hours worked driving tractor
-----------------
(1) {{{ a = 2b }}}
(2) {{{ 10a + 12b = 416 }}}
-----------------------
Substitute (1) into (2)
(2) {{{ 10*( 2b ) + 12b = 416 }}}
(2) {{{ 20b + 12b = 416 }}}
(2) {{{ 32b = 416 }}}
(2) {{{ b = 13 }}}
and, since
(1) {{{ a = 2b }}}
(1) {{{ a = 2*13 }}}
(1) {{{ a = 26 }}}
She pent 26 hrs at office and
13 hrs driving tractor
---------------------------
check:
(2) {{{ 10a + 12b = 416 }}}
(2) {{{ 10*26 + 12*13 = 416 }}}
(2) {{{ 260 + 156 = 416 }}}
(2) {{{ 416 = 416 }}}
OK