x^2 +105x-1050=1550please help

-x^2+105x-1050=1550
We move all terms to the left:
-x^2+105x-1050-(1550)=0
We add all the numbers together, and all the variables
-1x^2+105x-2600=0
a = -1; b = 105; c = -2600;
Δ = b2-4ac
Δ = 1052-4·(-1)·(-2600)
Δ = 625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
x1=−b−Δ√2ax2=−b+Δ√2a
Δ−−√=625−−−√=25 x1=−b−Δ√2a=−(105)−252∗−1=−130−2=+65 x2=−b+Δ√2a=−(105)+252∗−1=−80−2=+40