Question 1204237


the first mechanic charged {{{105}}} per hour, cost of his work is {{{105x}}} where {{{x }}}is number of ours
and the second mechanic charged{{{ 85}}} per hour, cost of his work is {{{85y}}} where {{{y}}} is number of ours

if the mechanics worked for a combined total of{{{ 20}}} hours, we have

{{{ x+y=20}}}....solve for {{{x}}}
{{{x=20-y}}}.....eq.1


 and, if  together they charged a total of {{{1800}}}, we have

{{{105x+85y=1800}}}......eq.2, substitute{{{ x}}} from eq.1
{{{105(20-y)+85y=1800}}}....solve for{{{ y}}}
{{{2100 - 105 y+85y=1800}}}
{{{2100-20y=1800}}}
{{{2100-1800=20y}}}
{{{300=20y}}}
{{{y=300/20}}}
{{{y=15}}}

go to eq.1

{{{x=20-y}}}
{{{x=20-15}}}
{{{x=5}}}

the  mechanic who charged {{{105}}} per hour, worked {{{5}}} hours
 the mechanic who charged {{{85}}} per hour, worked {{{15}}} hours