Question 1055438
Let {{{ t }}} = total income for the 
certain number of days
Let {{{ n }}} = the certain number of days
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given:
(1) {{{ t/n = 25 }}}
(2) {{{ ( t - 54 ) / ( n - 1 ) = 24 }}}
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(2) {{{ t - 54 = 24*( n - 1 ) }}}
(2) {{{ t - 54 = 24n - 24 }}}
(2) {{{ t - 30 = 24n
(1) {{{ n = t/25 }}}
Plug this result back into (2)
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(2) {{{ t - 30 = 24*(t/25) }}}
(2) {{{ t - 30 = t*( 24/25 ) }}}
(2) {{{ t - t*( 24/25 ) = 30 }}}
(2) {{{ t/25 = 30 }}}
(2) {{{ t = 750 }}}
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question:
Find {{{ n }}} if the average is 25
(1) {{{ t/n = 25 }}}
(1) {{{ 750/n = 25 }}}
(1) {{{ n = 750/25 }}}
(1) {{{ n = 30 }}}
For 30 days, the average is Rs 25
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Check my math & maybe get another opinion, too