John can clean the kitchen in 45 minutes.  When Freida helps him,they clean it in 20 minutes.  How long would Freida take by herself ?  i need help with solving this problem.

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To solve these types of problem take the rate, how much they clean in one minute John can clean 1/45 of the kitchen in one min and Freida 1/x ( we are looking for x) Together they take 20 mins So they can clean 1/20 of the kitchen in one minute 1/45+1/x=1/20 solving forx, x=36 mins So Frieda takes 36 mins by herself to clean the kitchen

Carlene -These are rate of work problems. The rate of work is the rate of some "job" being done, expressed as "jobs per time."In your problem the "job" is cleaning one kitchen. For John:rate = 1 kitchen /45 minThe combined rate for John and Freida:rate = 1 kitchen/ 20 minSo, the equation is:1/45 + f = 1/20, where f is Frieda's rate per jobf = 1/20 - 1/45 = 9/180 - 4/180 = 5/180 = 1/36So, Freida can clean 1 kitchen in 36 minutes.Rate = (1 kitchen) / (36 minutes)Always think of these rates as jobs/min or jobs/hour. When rates are written as jobs per time, you can add and subtract them as needed.Hope that helps

36 minutes