If you put brackets around (2+1), your method of working is:
1) 15-4*(2+1)=3
2) 15-4*3=3
3) 15-12=3
You don't need any more brackets, as the BIDMAS (brackets, Indices, division, multiplication, addition, subtraction) rule does the rest of the job for you.
The answer is therefore: 15-4*(2+1)=3
200t + 8t^3 - 80t^2
8t(25 + t^2 - 10t) ....rearrange
8t(t^2 - 10t + 25)
8t(t - 5)(t - 5)
8t(t - 5)^2 <==
Isosceles triangle means both base angles are the same. SO,
42+42= 84
a triangle has 180 degrees. 180-84=96
the vertex angle is 96 degrees
About 28.5 percent is the decrease I hope this helps :)
