math
posted by mi .
tom was paid $4.50 per hour for painting a fence and $ 6.50 per hour for mowing grass. He worked 7 hours and earned $39.50. How many hours did it take him to paint the fence/

the best way to go about this question is trial and error. if he worked 7 hours and made 39.50, then if he works 3 hours painting the fence, and 4 hours mowing the grass then he makes 39.50.
i'm sure you can make equations for it but it's much quicker and easier to go about this question this way. 
my 6th grade grandaughter needs an equation. than you.

george can you give me some additional help. thanks

x+y=7
4.5x+6.5y=39.5
Multiply the top equation by 4.5 to cancel the x's:
4.5x4.5y=31.5
4.5x+6.5y=39.5
2y=8
y=4
Put that back in the first equation to solve for x. 
You do NOT want to attempt this problem by trial and error.

I feel i may have stepped on some toes. I am sorry for that. I am not the most intelligent person in the world and I sincerly appoligize.

No need for an apology, George. I was simply saying that it's not the best method. :)