1.77245385
that is the answer
A=-.25+6.7t, s=.75+4.5t when Amir catches up a=s so:
-.25+6.7t=.75+4.5t add .25 to both sides
6.7t=1+4.5t subtract 4.5t from both sides
2.2t=1 divide both sides by 2.2
t=10/22 hr
t≈0.45 hr (to nearest hundredth)
I'd use synthetic div. here, with 2 as my divisor:
________________
2 / 1 -11 18
2 -18
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1 -9 0
Note that the coefficients of the missing factor are given here and are 1 and -9. Thus, (x-9) is the missing factor.