X-y=200
xy=mn
so
first equation times -1 and add x both sides
y=x-200
sub that for y in other equation
x(x-200)=min
x²-200x=min
take deritivive
2x-200=min
find where it equals 0
2x-200=0
2x=200
x=100
y=x-200
y=100-200
y=-100
the numbers aer 100 and -100
I liked using fractions for this type of question, I just find it easier, so in this case 20% is 1/5. That means that £45 is 4/5, so you have to divide 45 by 4 to get 1/5 of the original amount. 45 ÷ 4 = 11.25. Then, you just multiply 11.25 by 5 to get £56.25, which should be the answer. Hope this helped!
Answer: it's 80 because h = -16t2 + 64 = 80
5/7 due to dividing the least common facter to both of them