(2x+1)=Jeremy´s age
(2x+3)=Sam´s age.
we suggest this equation:
(2x+1)(2x+3)=783
4x²+6x+2x+3=783
4x²+8x-780=0
x²+2x-195=0
We solve this quadratic equation:
x=[-2⁺₋√(4-4*1*(-195))]/2=(-2⁺₋28)/2
x₁=(-2-28)/2=-15 this solution is not valid.
x₂=(-2+28)/2=13
Jeremy´s age=2x+1=2*13+1=27
Sam´s age=2x+3=2*13+3=29
1. Is correct
2. x^2 - 12
3. 2 / (a-1)
There are 8 more dairy cattle on the farm than beef cattle.

Or, if that hyphen between the lower index and 3 is actually a negative sign, then the sum is -189.
Each part is 1/4 of a whole. There are 12/4 in all. 12/4=3