According to your chart, it costs $6241 per month to have two kids.
Split this evenly amongst the two parents to get 6241/2 = 3120.50
Each parent needs to make $3,120.50 per month.
There are about 4 weeks to a month, which means the weekly pay needs to be 3,120.5/4 = 780.125 which rounds to 780.13
Each parent needs to earn $780.13 per week.
Then divide this over 40 to get 780.13/40 = 19.50325 which rounds up to 19.51
The hourly wage per parent must be $19.51
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Another approach:
1 week = 40 hours of work
4 weeks = 4*40 = 160 hours of work
1 month = 4 weeks (approximate)
1 month = 160 hours of work
Each parent needs to make $3,120.50 per month, so each wage needs to be 3120.50/160 = 19.503125 which rounds up to 19.51
Side note: The above calculations are for full-time workers. If you go for part-time, then you'll need to double the wage since part-time workers work half as often compared to full-time. Either that or the parent would have to get 2 jobs (at most a total of 4 jobs combined from both parents)