Problem solving strategy/ work backward

momtocam

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On Sunday Lars walked three times as far as he did on Saturday. On Monday Lars walked 3 more miles than on Sunday. On Tuesday, Lars walked 2 less miles than on Monday. Lars walked 7 miles on Tuesday. How many miles did Lars walk on Saturday?
 
momtocam said:
On Sunday Lars walked three times as far as he did on Saturday. On Monday Lars walked 3 more miles than on Sunday. On Tuesday, Lars walked 2 less miles than on Monday. Lars walked 7 miles on Tuesday. How many miles did Lars walk on Saturday?

Assume Lars walked on Saturday 'S' miles

Lars walked on Sunday = 3S miles

Lars walked on Monday = 3S + 3 miles

Lars walked on Tuesday = 3S + 1 miles

Now continue....
 
I still can't figure out the answer and this is 4th grade map. I just left a question mark next to it for my son to turn in tomorrow. Thanks for your help. I love this site. Math was never my cup of tea...........And I am 45 yrs old now. Thanks so much again........
 
oh its fourth grade - then

Lars walked on tuesday 7 miles

Lars walked on Monday 9 (=7+2) miles On Tuesday, Lars walked 2 less miles than on Monday

Lars walked on Sunday 6 (=9-3) miles On Monday Lars walked 3 more miles than on Sunday

Lars walked on Saturday ??? miles On Sunday Lars walked three times as far as he did on Saturday
 
momtocam said:
I just left a question mark next to it for my son to turn in
Um... Why were you doing his homework...? :shock:

Meanwhile, if you aren't comfortable with using variables, use pictures. (This is what my eleven-year-old uses.)

Let a square be the "size" of the distance for Saturday.

How many squares stand for the distance for Sunday?

How many squares, plus a number, stand for the distance for Monday? What is the number?

How many squares, plus and then minus number, stand for the distance on Tuesday? What is (the final value of) the number?

If Tuesday's squares and number are equal to 7, then how much is a square?

Then how much was Saturday?

(Alternatively, you could always work backwards from Tuesday....)

Eliz.
 
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