Question 1180357


let  Pedro’s age be {{{x}}} and his grandfather’s age {{{y}}}


if Pedro is {{{48}}} years younger than his grandfather, then

{{{x=y-48}}}............eq.1

if in {{{5}}} years, his grandpa will be {{{five }}}{{{times}}} his age, we have

{{{5(x+5)=y+5}}}

{{{5x+25=y+5}}}........eq.2

solve the system:

{{{x=y-48}}}............eq.1
{{{5x+25=y+5}}}........eq.2
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substitute {{{x}}} from eq.1 in eq.2

{{{5(y-48)+25=y+5}}}........eq.2, solve for {{{y}}}

{{{5y-240+25=y+5}}}

{{{5y-215=y+5}}}

{{{5y-y=215+5}}}

{{{4y=220}}}

{{{y=55}}}

go to

{{{x=y-48}}}............eq.1,substitute {{{y}}}

{{{x=55-48}}}

{{{x=7}}}


 Pedro is {{{7}}} years old.