Eight hours.
43*15 = 43*(10+5) = 430 +430/2 = 430 + 215 = 645.\the exact answer is 648.24, an error of one half of one percent.
7 and one half hours 430 miles
120% of 430= 120% * 430= 1.2 * 430= 516
20% of 430= 20% * 430= 0.2 * 430= 86
17% of 430= 17% * 430= 0.17 * 430= 73.1
85% of 430 = 85% * 430 = 0.85 * 430 = 365.5
84% of 430 = 361.2= 84% * 430= 0.84 * 430= 361.2
18% of 430= 18% * 430= 0.18 * 430= 77.4
430
7.65% of 430:= 7.65% x 430= 0.0765 x 430= 32.895
18% of 430= 18% * 430= 0.18 * 430= 77.4