Question 1014043
Let {{{ x }}} = the cost of the other 2 books combined
Let {{{ c }}} = the cost of the most expensive book
(1) {{{ c + x = 150 }}}
(2) {{{ c = 1.5x }}}
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Substitute (2) into (1)
(1) {{{ 1.5x + x = 150 }}}
(1) {{{ 2.5x = 150 }}}
(1) {{{ x = 60 }}}
and
(2) {{{ c = 1.5x }}}
(2) {{{ c = 1.5*60 }}}
(2) {{{ c = 90 }}}
the cost of the most expensive book was $90
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check:
(1) {{{ c + x = 150 }}}
(1) {{{90 + 60 = 150 }}}
(1) {{{ 150 = 150 }}}
OK