Question 108343
Maria practiced the recorder for {{{40- minutes}}} on Saturday. 
She practiced {{{10- minutes- less}}} in the {{{afternoon}}} than in the {{{morning}}}. 
How many minutes did Maria practice in the {{{morning}}}? 

If {{{in- the- morning = x}}} and {{{in-the-afternoon = y}}}, then we have:

{{{x + y = 40}}}

Since she practiced {{{10- minutes- less}}} in the {{{afternoon}}} than in the {{{morning}}}, we can write:


{{{x-10 = y}}}…… we will substitute it in previous formula:

{{{x + y = 40}}}


{{{x}}} + {{{x}}} – {{{10}}} = {{{40}}}

{{{2x}}} – {{{10 }}}= {{{40}}}

{{{2x = 40 + 10}}}

{{{2x = 50}}}…..divide both sides by {{{2}}}

{{{x = 25}}}………she practice in the morning {{{25 }}} minutes…

And in the afternoon:

{{{y = x – 10}}}

{{{y = 15}}} she practice {{{15 }}} minutes

Check:

{{{x + y = 40}}}

{{{25 + 15 = 40}}}

{{{40 = 40}}}