+80 A fruiterer has some apples on sale. On Monday, 3/7 of the apples and an additional 7 boxes were sold. On Tuesday, 3/5 of the remaining and an additional 5 boxes were sold. If
13 boxes of apples were left, how many boxes of apples were there at first ?
+313 Let there were x boxes of apple at first.
Monday sold : \( {3\over7 }x + 7{}{}\)
Remaining : \( x -({3 \over 7}x + 7) = {}{}\)\({4 \over 7}x - 7{}{}\)
Tuesday sold: \({3\over 5}({}{}\)\( {4 \over 7}x-7)+5 ={}{}\)\( {12 \over 35}x+{}{}\)\( {4 \over 5}{}{}\)
Remaining: 13
Set and equation :
x - \( ({3 \over 7}x+7)-{}{}\)\( ({12 \over 35}x+{}{}\)\( {4 \over 5}){}{}\) =13
x - \( {3 \over 7}x-7-{}{}\)\( {12 \over 35}x-{}{}\)\( {4\over 5}=13{}{}\)
\({8 \over 35}x ={}{}\)\( {104\over 5}{}{}\)
\(x\) = 91 (boxes)
There were 91 boxes of apples at first
{ Total boxes -- Monday sold -- Tuesday sold = 13 }
