Question 606562
Let their amounts = 
(1) {{{ a + b + c = 35 }}}
(2) {{{ b = (3/4)*( a + c ) }}}
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(2) {{{ a + c = (4/3)*b }}}
substitute (2) into (1)
(1) {{{ (4/3)*b + b = 35 }}}
(1) {{{ (7/3)*b = 35 }}}
(1) {{{ b = (3/7)*35 }}}
(1) {{{ b = 15 }}}
Bob has $15