CPhill

3/14 - 9   =   3/14 -  126/14  = -123/14

OR

3 / [14 - 9]  = 3 / 5

(1 + 3/5) + ( 2 + 5/6)  =

1 + 2 + 3/5 + 5/6       =

3  + 3/5 + 5/6     and gettig a common denominator of  30 for the fractions, we have

3 + 18/30 + 25/30  =

3 + 43/30  =

3 + 1 + 13/30  =

4 + 13/30

Edit

Both are rational

For the first, we have   4 + 21/99  = 4 + 7/33 =  139/33

For the second, we have   2.78   =  2 + 78/100   =  278/100  = 139/50

Thanks, guys, for pointing out my earlier error.....however.....the "Guest's" answer of 41/100  is not correct because the "21" part does not repeat

Check to see that 139/33 results in a "repeating"  decimal part of "21"

168 / 2   = 84

Two   .....here are the rules.......http://www.usca.edu/chemistry/genchem/sigfig.htm

y=x^2+7x-8     this is a parabola that turns upward

The x coordinate of the vertex is = -7/2(1)  = -7/2 = -3.5

The y coordinate of the vertex is  (-3.5)^2 + 7(-3.5) - 8  = -81/4 = -20.25

Factoring to find the roots, we have...  (x -1) (x + 8)  = 0   setting each factor to 0  rhe roots are  x= 1 and x = -8

Here's the graph..........https://www.desmos.com/calculator/jibcea03br

-1/2  - 5/4      get a common denominator  of 4

-2/4  - 5/4  =

-7/4

tan = y/x

We need to find r  which =  sqrt(x^2 + y^2)  = sqrt(8^2 + 15^2)  = sqrt(289)  = 17

So

sin (j)   = y / r   =  15 / 17

(1/3) 249  = 80

(1/6) 240  = 40

(1/2) 240  = 120

We need 3 times as much of each....so......

2 + 1/3 = 7/3    and   1 + 1/4   = 5/4     and we have

3(7/3)  = 7 cups of flour

3(5/4)   = 15/4  = 3 + 3/4   cups of sugar