Hank S. answered 07/22/15
Tutor
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Fourth Year Math Major
1)Notice every term has a s term, a g term, and a factor of 7. Therefore we may write it as 7*s*g(36*S2 -84s*g+49*g2). Next notice 36=62, 49=72, and 84=2*6*7. There it may be factored to 7*s*g(6s-7g)2.
2) Since a boost of 3mph leads to an increase of 21 miles, it implies Roger walked for 7 hours. Now, if he were to walk at 2 mph for the entire trip, he would only travel 14 miles, which is 4 miles too little. Therefore he had to walk for 2 hours at 4 miles to walk 18 miles.