Answer:15) 300%Step-by-step explanation:15) Let the item originally cost n dollars.The new incorrect price is (n-.6n).So we want to find k such that (n-.6n)+k(n-.6n)=n+.6nsince we actually wanted it to be (n+.6n).So we have (n-.6n)+k(n-.6n)=n+.6nDistribute:n-.6n+kn-.6nk=n+.6nSubtract n on both sides -.6n+kn-.6nk=.6nWe are trying to solve for k. So add .6n on both sides:kn-.6nk=1.2nDivide both sides by n:k-.6k=1.2.4k=1.2Divide both sides by .4k=1.2/.4k=3So 3=300%.The incorrect price must be increased by 300% to get to the proper new price.Here is an example:Something cost $600.It was reduce by 60% which means it cost 600-.6(600)=600-360=240This was the wrong price.We needed it to be increased by 60% which would have been 600+360=960.So we need to figure out what to increase I wrong price 240 to to get to our right price of 960.240+k(240)=9601+k=960/2401+k=4k=3So 240*300%+240 would give me my 960.16) Speed=distance/timeIn the first half hour, she traveled 5 miles (8:30 to 9).In 1/3 hour she traveled (5-2)=3 miles (9 to 9:20).We are told not to do anything where she stayed still.In the last half hour, she traveled (2-0)=2 miles (9:30 to 10).The average speed=[tex]\frac{5+3+2}{\frac{1}{2}+\frac{1}{3}+\frac{1}{2}}=\frac{10}{\frac{4}{3}}=\frac{10(3)}{4}=\frac{30}{4}=\frac{15}{2}=7\frac{1}{2}[/tex].