First, let's convert hours to seconds:
#5" hrs" xx (60" min")/"hr" xx (60" sec")/"min" =>#
#5color(red)(cancel(color(black)(" hrs"))) xx (60color(blue)(cancel(color(black)(" min"))))/color(red)(cancel(color(black)(" hr"))) xx (60" sec")/color(blue)(cancel(color(black)(" min"))) =>#
#5 xx 60 xx 60" sec" => 300 xx 60" sec" => 18000" sec"#
#5" hrs" = 18000" secs"#
And #$90 = 9000" cents"#
We can write a relationship to find how many seconds it takes to earn 25 cents and solve for #s#:
#s/(25 " cents") = (18000" secs")/(9000" cents")#
#s/(25 " cents") = (color(red)(cancel(color(black)(18000)))^2" secs")/(color(red)(cancel(color(black)(9000)))^1" cents")#
#s/(25 " cents") = (2" secs")/(" cents")#
#color(red)(25)color(red)(" cents") xx s/(25 " cents") = color(red)(25)color(red)(" cents") xx (2" secs")/(" cents")#
#cancel(color(red)(25)color(red)(" cents")) xx s/color(red)(cancel(color(black)(25 " cents"))) = color(red)(25)cancel(color(red)(" cents")) xx (2" secs")/color(red)(cancel(color(black)(" cents")))#
#s = color(red)(25) xx 2" secs"#
#s = 50" secs"#
It takes Clare 50 seconds to earn 25 cents.
