ElectricPavlov

12 % off means you pay 88% of original price 'x'

.88x     now add 6% tax:      final price =   .88x * 1.06 =   .9328 x

Put in x = 0    and yo will find     c = 0

then put in x = 1   and you will find    a + b  = 2

then put put in x = 8 to find              4a + 2b = 8        Solve the red equations for   a   and  b      then you can sub in x = 3 for your answer

For a round trip the uphill = downhill distances   and the flat = 16 km 

   so   U = D        Total roundtrip distance = U + U + F                                       U = uphill   D = downhill

U/100 + U/50   + 16 / 80 = 5 hours

(U + 2U) / 100 = 4.8

results in

U =160     and   F = 16    and  D = 160     ( roundtrip )

     total ONE-WAY distance =  (  160+160+ 16 )/ 2 = 168 km

_+-5=4             add + 5 from both sides of the equation....

a - b = 2 (c+d)          but b = a-2    sub that in

a - ( a-2)  = 2 ( c+d)

2 = 2 ( c+d)

1 = c+d                 now   d = c+8     sub that in

1 = c   + c+8

1 = 2c + 8

-7 = 2c

c = - 7/2

_ - 5 = -9     add +5 to both sides

_  = - 4

Cphill is correct....    I AGAIN missed the tiny ' - ' sign !

Use a calculator to find    arc cos (.111) = ~ 84 degrees

ax^2+bx+c,       when x = 0       then    c = 4

Since it is 'monic'    we know   a = 1

y  =  x^2 +bx   + 4       now when x= 1

10= 1^2 + b + 4      shows b = 5

y = x^2 + 5x + 4

y = 5/4 x + b     is the gneral form.....plug in the point given to solve for 'b'

1 = 5/4 (4) + b    shows  b = -4

y = 5/4 x -4