On monday 350 people bought tickets

C

Step-by-step explanation:

If you use substitution,  you will figure out that x=350-y, and 3x=1050-3y. If you plug this into the equation, 1050-3y+7y=2050.

Simplifying, we get 1050+4y=2050, and 4y=1000.

Divide each side by 4 to get y=250.

i think it's ф or x=6,-6

step-by-step explanation:

-x^2=-36

x^2=-36

ф

or

if you mean by : -(x^2)=-36

it'll be: x^2=36

x=6,x=-6

hope it'll ! have a good day!

you for asking!